w'bob, so the 3/16" tore at the transverse weld? That let the two adjoining compartments' bottom plate hole? That implies the tear/hole was right at the two welds either side of the bulkhead?
So, this is a case of a welded boat holing the bottom by hitting some sunken steel?
Interesting, the design to continuous weld the bottom (transverse) bulkheads to make them 'water tight' actually ended up softening the bottom along those welds (HAZ) enough to allow them to be holed?
Kind of ironic? If the impact zone was in the field (away from HAZ near framing welds) and then scored until it hit the HAZ of the transverse..... the material is still 'bullet proof'/stiff until we compromise it with that weld.
Interesting to note that if the bottom was framed entirely longitudinally (on the skin/plate/shell) and only skip welded; some other outcome may have resulted? Has any other skiff in your shop had similar impact and bottom hole?
Cheers,
Kevin Morin
Foam OR No Foam?
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kmorin
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Re: Foam OR No Foam?
kmorin
Re: Foam OR No Foam?
I don't think I put it too clearly last night, sorry. We came back one night and the boat behind us, trying to put it on the trailer in a cross current, he missed, ran it up on top of a steel pier at about 3/4 throttle before backing off and rolling back into the water. Eventually we got him on the trailer without noticing anything wrong, it was real cold and dark and we were eating oysters and no one thought to look for damage.
The next day we hunted, came back, put our boat on the trailer, the other boat came in behind us and as he put it on the trailer the water was pouring out the hole he'd put in it the night before. There was a good bit of water in there, like pulling a drain plug and letting it drain for two or three minutes. The hole looked like a piece of paper folded the long way, not a big visible puncture but enough to let in, and out, a lot of water. Maybe freezing had nothing to do with it ... in fact probably not ... but it is probably for the best that whatever water got in, came right back out again once it thawed and the boat was back on the trailer, instead of getting trapped in there and going through a winter's worth of freeze-thaw-freeze cycles. Maybe I'm just paranoid about that but i can't imagine it does a hull any good.
The next day we hunted, came back, put our boat on the trailer, the other boat came in behind us and as he put it on the trailer the water was pouring out the hole he'd put in it the night before. There was a good bit of water in there, like pulling a drain plug and letting it drain for two or three minutes. The hole looked like a piece of paper folded the long way, not a big visible puncture but enough to let in, and out, a lot of water. Maybe freezing had nothing to do with it ... in fact probably not ... but it is probably for the best that whatever water got in, came right back out again once it thawed and the boat was back on the trailer, instead of getting trapped in there and going through a winter's worth of freeze-thaw-freeze cycles. Maybe I'm just paranoid about that but i can't imagine it does a hull any good.
Re: Foam OR No Foam?
Good Morning Kevin,
No we haven't seen any else like that. The same customer dropped a green-heart piling hanging from the crane. It bounced off the center console smashing the steering wheel and control. It the hit the deck and left a small dent. It is amazing how these guys staying in business before they discovered the miracle l l metal.
We had one of our 20' Sea mules (our name for our flat bottom boats) in the cofferdam of the world trade center when it collapsed Fortunately the crew that was changing anodes down there had come out for coffee break when it all happened. The boat was dug out and returned to the company a year and a half later. We pressure washed the whole thing, repainted the bottom and changed the "D" rubber. The only scar was a dent in the side,of course the whole boat was dented before the collapse. To my knowledge the boat is still on the job.
welderbob
No we haven't seen any else like that. The same customer dropped a green-heart piling hanging from the crane. It bounced off the center console smashing the steering wheel and control. It the hit the deck and left a small dent. It is amazing how these guys staying in business before they discovered the miracle l l metal.
We had one of our 20' Sea mules (our name for our flat bottom boats) in the cofferdam of the world trade center when it collapsed Fortunately the crew that was changing anodes down there had come out for coffee break when it all happened. The boat was dug out and returned to the company a year and a half later. We pressure washed the whole thing, repainted the bottom and changed the "D" rubber. The only scar was a dent in the side,of course the whole boat was dented before the collapse. To my knowledge the boat is still on the job.
welderbob
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welder
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Re: Foam OR No Foam?
Bob, any pictures of the boat?welderbob wrote:Good Morning Kevin,
No we haven't seen any else like that. The same customer dropped a green-heart piling hanging from the crane. It bounced off the center console smashing the steering wheel and control. It the hit the deck and left a small dent. It is amazing how these guys staying in business before they discovered the miracle l l metal.
We had one of our 20' Sea mules (our name for our flat bottom boats) in the cofferdam of the world trade center when it collapsed Fortunately the crew that was changing anodes down there had come out for coffee break when it all happened. The boat was dug out and returned to the company a year and a half later. We pressure washed the whole thing, repainted the bottom and changed the "D" rubber. The only scar was a dent in the side,of course the whole boat was dented before the collapse. To my knowledge the boat is still on the job.
welderbob
Lester,
PacificV2325, Honda BF225
2386
PacificV2325, Honda BF225
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Sabs28
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Re: Foam OR No Foam?
Are there any alternatives to "spray-in foams" for flotation?? Is the whole point of foaming a boat to keep it afloat incase of hull breach or to displace water so it will not compltely sink if water can get in the hull?? Or both???? I see the point of "Not Foaming" a boat due to the corrosion issue. But if the boat sinks it would be an Alloy wreck on the ocean/ lake/river bottom. If you do get it back, motor, electronics are junk. So what would be the point?? I know it would have to be a really hard hit to put a whole in a 1/4 inch bottom, But lets face facts, some times "Shat Happens". 
I guess my question is; How come no one can come up with a solution so you can foam a hull in some way that gives you the best of both worlds without turning the boat into an Alka Seltzer??????
I am just a little surprised this is still a problem.
Just my opinion, And No, I am not trying to start a fight.
I guess my question is; How come no one can come up with a solution so you can foam a hull in some way that gives you the best of both worlds without turning the boat into an Alka Seltzer??????
I am just a little surprised this is still a problem.
Just my opinion, And No, I am not trying to start a fight.
Re: Foam OR No Foam?
In our one model of work boats we use rigid board foam. It doesn't lay on the bottom. Its in a watertight compartment. I you had to remove it ,it would be easy once you cut the deck open. Safe boats uses a closed cell foam and they sew it into a sealed bag. (at least that's what I've be told). You could also fill the compartment with Ping pong type balls,again put them in some sort of mesh bag.
Welderbob
Welderbob
Re: Foam OR No Foam?
I wrestled with the foam issue and spent a fair amount on the USCG site using their calculators and recommendations. As far as the sealed watertight compartments, unless something has changed in the last few years with the regs, the CG gives them zero value for flotation. As a matter of fact if you're going to do a dynamic test these compartments have to be opened so they can fill with water. Not saying this makes any sense but that's the rule. Of course, only smaller craft are required to have flotation at all.
If you're going to put flotation in, the bottom of the hull is the absolute worst place to put it. That will make your boat turn and float turtle. It's also a nightmare for corrosion in the bilges. It belongs in gunwales and areas above the bilge if installed at all. I ended up calculating level flotation for our cat and installed foam wedged between frames which also simplified interior finish. Some of the 2" foam panels were wrapped in colored neoprene sheet before being placed which makes a reasonably attractive wall finish and potrudes out a bit from the deadly transverse frames to save skin. The inside of the pilothouse including the underside of roof is fitted with panels in the same fashion, these wrapped in vinyl before installation. Keeps the house nice and cool, even in the broiling Tx. heat of summer.
I'm now, after using the boat nine years, pulling the interior such as it is, got tired of building and decided to go fishing before finishing, cleaning it and fixing a few corrosion pits on bottom plate, the result of not removing mill scale before and having stagnant water trapped there, along with some Rule bilge pumps which will be relocated on nylon standoffs well above the bottom It appears there was some current leakage from these pumps. I intend to replace the foam, primarily for sound and heat insulation, but will paint it with an elastomeric paint before reinstalling it. The stuff is flammable and I want to mitigate the risk. As calculated, my boat will float level with powerheads above water if it is completely swamped. It's also divided into watertight compartments but I'm a belt and suspenders kind of guy. The boat is a Roger Hill 8.5 meter aluminum pilothouse style cat. I'm also pleased to report that after nine years of hard offshore use I've had a grand total of one weld crack, this one was between a longitudinal stringer and hull and wasn't a great fit to start with....the weld gap was excessive. This was my brother's and I first experience with alum welding and while the welds lack the beauty that years of technical expertise provide, they've proven to be plenty strong and durable. Everything was welded with a PowerMig 300 + Python push pull, most of the welds were pulse mode. This was a very complex boat for first build but has always been pleasing to my eye.
Chuck
If you're going to put flotation in, the bottom of the hull is the absolute worst place to put it. That will make your boat turn and float turtle. It's also a nightmare for corrosion in the bilges. It belongs in gunwales and areas above the bilge if installed at all. I ended up calculating level flotation for our cat and installed foam wedged between frames which also simplified interior finish. Some of the 2" foam panels were wrapped in colored neoprene sheet before being placed which makes a reasonably attractive wall finish and potrudes out a bit from the deadly transverse frames to save skin. The inside of the pilothouse including the underside of roof is fitted with panels in the same fashion, these wrapped in vinyl before installation. Keeps the house nice and cool, even in the broiling Tx. heat of summer.
I'm now, after using the boat nine years, pulling the interior such as it is, got tired of building and decided to go fishing before finishing, cleaning it and fixing a few corrosion pits on bottom plate, the result of not removing mill scale before and having stagnant water trapped there, along with some Rule bilge pumps which will be relocated on nylon standoffs well above the bottom It appears there was some current leakage from these pumps. I intend to replace the foam, primarily for sound and heat insulation, but will paint it with an elastomeric paint before reinstalling it. The stuff is flammable and I want to mitigate the risk. As calculated, my boat will float level with powerheads above water if it is completely swamped. It's also divided into watertight compartments but I'm a belt and suspenders kind of guy. The boat is a Roger Hill 8.5 meter aluminum pilothouse style cat. I'm also pleased to report that after nine years of hard offshore use I've had a grand total of one weld crack, this one was between a longitudinal stringer and hull and wasn't a great fit to start with....the weld gap was excessive. This was my brother's and I first experience with alum welding and while the welds lack the beauty that years of technical expertise provide, they've proven to be plenty strong and durable. Everything was welded with a PowerMig 300 + Python push pull, most of the welds were pulse mode. This was a very complex boat for first build but has always been pleasing to my eye.
Chuck
Texian, born and bred.
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kmorin
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Re: Foam OR No Foam?
Chuck, I think the regulations for flotation are divided under and over 20' LOA, but I'm not exactly sure if that includes 'transom plane to bow tip', or, if an engine cantilever would measure into the regulations LOA?
I think many welded builders spend most effort in the Over20' class to avoid fiddling with these very poorly thought out regulations? As you mentioned you're supposed to flood the voids in a level flotation test! This almost assures they have to be filled with foam to pass.
I don't include air flotation chambers in my smaller skiffs I use "nitrogen filled, hollow, box-beams" that would be "structurally compromised" by being filled with water. So I've tended to avoid that silliness on the part of the "federales", however, I'm not a full time builder or manufacturer that would draw attention.
The location of an air void below decks is primarily for the 95+% of the time when the boat sheds the water it takes on deck below the topsides/gunwales and not solely for the catastrophic 'stop from sinking' condition IMO. By having the void below decks the entire buoyancy is converted to lift to clear the decks when they're flooded by a green one over the topsides.
Of course, this is usually only a concern with open skiffs. Regardless of size they need to be able to drain out the freeing ports (scuppers) or they'd be left to pump out any water they took over the sides.
Whether this deck should be welded in, or dead plants in glued sheets and bolted to the frame- may be a question; but I think these decks are installed to deal more with the 95+% events than to deal with the 'save-the-boat' condition?
I completely agree with locating some more flotation in the upper parts of the boat, especially if it has a cabin, that added flotation in the upper structure will make the flooded stability greater.
But I think the issue of foam for larger hulls (>20' LOA) still comes back to my main question of the practice?
If you have a welded boat, and there is a welded deck, then to finalize and confirm ("Trust; but Verify"- Ronaldus Magnus) the weld integrity TIG, MIG, Laser, or any kind of weld, a pressure test of the void's seal welds is imperative. In other words, that section of the boat is nothing more than a welded 'tank' like a gasoline or fuel tank.
If that is the case, then shouldn't it have the same exact integrity? And if the entire hull should have the same integrity of a tank, then why put a failure state anticipation for the 'tank' because it could rupture? Before I'd put foam in I'd move from 1/4" up to 5/16" or 3/8".
If I thought there was some/any/imaginable risk of hull rupture nothing (!) in my way of thinking adds some 'sit-it-out-while-swamped' foam. [ FULL DISCLOSURE: Sitting it out here in our local waters just allows the family to have a funeral instead of a memorial service. ] My thinking goes exclusively to ADD METAL. What does another 1/16" of hull cost? If you add labor to the foam, the sealing and install effort I will guaran-darn-tee that the thicker hull will cost less and add more to the boat's integrity over the foam.
The foam (to me) totally presumes the boat will be holed: my cure? more metal.
Why exactly do you/we/me/owners have a welded aluminum boat anyway? Is there something about the material that seemed like a better choice as a boat?
We moved on to the potential for rupturing hulls, the only instance we've got is
#1. a 3/16" hull bottom torn around a HAZ,
#2 A work boat run over steel sunken wreck
#3 and some corrosion leaks or maintenance issues.
All of these seem to beg the point to me?
I still remain convinced that foam is an expense and effort that doesn't return that to me. Besides which we have more cases of foam related problems than we can count, I've done more foam bottom and tank repair than any other single cause in the last 40 years. I've not seen one skiff lost to holing the hull but have seen many damaged or 'lost' (repairs approaching a new skiff cost) to corrosion holes from improperly installed or the wrong composition "foam jobs".
I'd rather rely on the metal, welded correctly and checked for integrity.
To me, adding foam is money illogically spent on a metal boat. I'm not opposed if it's used as insulation for sound, heat, cooling, or even some sandwich panels for structural uses, but added to float the boat because it is designed poorly or built poorly- not for this old, heavy displacement skiff builder.
cheers,
Kevin Morin
I think many welded builders spend most effort in the Over20' class to avoid fiddling with these very poorly thought out regulations? As you mentioned you're supposed to flood the voids in a level flotation test! This almost assures they have to be filled with foam to pass.
I don't include air flotation chambers in my smaller skiffs I use "nitrogen filled, hollow, box-beams" that would be "structurally compromised" by being filled with water. So I've tended to avoid that silliness on the part of the "federales", however, I'm not a full time builder or manufacturer that would draw attention.
The location of an air void below decks is primarily for the 95+% of the time when the boat sheds the water it takes on deck below the topsides/gunwales and not solely for the catastrophic 'stop from sinking' condition IMO. By having the void below decks the entire buoyancy is converted to lift to clear the decks when they're flooded by a green one over the topsides.
Of course, this is usually only a concern with open skiffs. Regardless of size they need to be able to drain out the freeing ports (scuppers) or they'd be left to pump out any water they took over the sides.
Whether this deck should be welded in, or dead plants in glued sheets and bolted to the frame- may be a question; but I think these decks are installed to deal more with the 95+% events than to deal with the 'save-the-boat' condition?
I completely agree with locating some more flotation in the upper parts of the boat, especially if it has a cabin, that added flotation in the upper structure will make the flooded stability greater.
But I think the issue of foam for larger hulls (>20' LOA) still comes back to my main question of the practice?
If you have a welded boat, and there is a welded deck, then to finalize and confirm ("Trust; but Verify"- Ronaldus Magnus) the weld integrity TIG, MIG, Laser, or any kind of weld, a pressure test of the void's seal welds is imperative. In other words, that section of the boat is nothing more than a welded 'tank' like a gasoline or fuel tank.
If that is the case, then shouldn't it have the same exact integrity? And if the entire hull should have the same integrity of a tank, then why put a failure state anticipation for the 'tank' because it could rupture? Before I'd put foam in I'd move from 1/4" up to 5/16" or 3/8".
If I thought there was some/any/imaginable risk of hull rupture nothing (!) in my way of thinking adds some 'sit-it-out-while-swamped' foam. [ FULL DISCLOSURE: Sitting it out here in our local waters just allows the family to have a funeral instead of a memorial service. ] My thinking goes exclusively to ADD METAL. What does another 1/16" of hull cost? If you add labor to the foam, the sealing and install effort I will guaran-darn-tee that the thicker hull will cost less and add more to the boat's integrity over the foam.
The foam (to me) totally presumes the boat will be holed: my cure? more metal.
Why exactly do you/we/me/owners have a welded aluminum boat anyway? Is there something about the material that seemed like a better choice as a boat?
We moved on to the potential for rupturing hulls, the only instance we've got is
#1. a 3/16" hull bottom torn around a HAZ,
#2 A work boat run over steel sunken wreck
#3 and some corrosion leaks or maintenance issues.
All of these seem to beg the point to me?
I still remain convinced that foam is an expense and effort that doesn't return that to me. Besides which we have more cases of foam related problems than we can count, I've done more foam bottom and tank repair than any other single cause in the last 40 years. I've not seen one skiff lost to holing the hull but have seen many damaged or 'lost' (repairs approaching a new skiff cost) to corrosion holes from improperly installed or the wrong composition "foam jobs".
I'd rather rely on the metal, welded correctly and checked for integrity.
To me, adding foam is money illogically spent on a metal boat. I'm not opposed if it's used as insulation for sound, heat, cooling, or even some sandwich panels for structural uses, but added to float the boat because it is designed poorly or built poorly- not for this old, heavy displacement skiff builder.
cheers,
Kevin Morin
kmorin
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Challenge
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Re: Foam OR No Foam?
Ok guys, I read through this link and also did a search and I could not find out how/what type of foam Pacific uses "below decks" sorry if I missed it!
Cheers
Rick
Rick you probably wont and they wont tell you how it's installed , how it drains or any of that trade secrete stuff.
Again, if the right foam is used and installed correctly there are no issues.
Pacific will sell you a boat with NO FOAM in it , no problem, it's the customers call.
Cheers
Rick
Rick you probably wont and they wont tell you how it's installed , how it drains or any of that trade secrete stuff.
Again, if the right foam is used and installed correctly there are no issues.
Pacific will sell you a boat with NO FOAM in it , no problem, it's the customers call.
Re: Foam OR No Foam?
One thing that I have read I in this thread has sort of not made sense to me, maybe I have misunderstood or read it incorrectly, but to say if foam was added to the hull below deck the boat will have more chance of going turtle if swamped or hit by a green-one?
Floatation is floatation be it either foam or air filled pockets, in theory the foamed boat will be less likely to turtle than the air filled hull because of the extra weight,minimal as it maybe still comes into the equation.
One other point that tends to bother me also, is we like to talk about the sealed, self draining deck. This is not the issue but the height of the deck above waterline and the scupper setup could be. Can I put forward a hypothetical question.
lets say we have a hull with no foam and a sealed self draining deck say at an average 4-5" above waterline as found on most 20' odd boats. We incur a small leak could be corrosion or a raw water pipe if an inboard, even a live bait tank fitting. For some reason the bilge pump/pumps fail to start and no alarms are set off. We all realize that no mater how the water the leak starts out, could be small, as we add more and more water and the hull starts to sink lower and lower the faster the leak becomes. The more water added to the hull the lower it sits and before long that 4-5" deck clearance above waterline becomes 0-1" and than we have water entering the deck through the scuppers and things escalate very quickly from there.
Assumption with foam possibly you may have the buoyancy to still keep the deck above waterline in that scenario
I personally believe we need something more than air chambers under our decks, is foam the best option? well I think there are better ones, but its still a viable one, and defiantly better than nothing at all. If all its there for is to keep the hull afloat if rolled over, then its a waste of time, buy a life raft. Even by putting the foam higher up will achieve nothing in my thoughts, I can't see how you will ever get enough of it to be practical and buy the time water reaches it do anything its too late anyway.
Floatation is floatation be it either foam or air filled pockets, in theory the foamed boat will be less likely to turtle than the air filled hull because of the extra weight,minimal as it maybe still comes into the equation.
One other point that tends to bother me also, is we like to talk about the sealed, self draining deck. This is not the issue but the height of the deck above waterline and the scupper setup could be. Can I put forward a hypothetical question.
lets say we have a hull with no foam and a sealed self draining deck say at an average 4-5" above waterline as found on most 20' odd boats. We incur a small leak could be corrosion or a raw water pipe if an inboard, even a live bait tank fitting. For some reason the bilge pump/pumps fail to start and no alarms are set off. We all realize that no mater how the water the leak starts out, could be small, as we add more and more water and the hull starts to sink lower and lower the faster the leak becomes. The more water added to the hull the lower it sits and before long that 4-5" deck clearance above waterline becomes 0-1" and than we have water entering the deck through the scuppers and things escalate very quickly from there.
Assumption with foam possibly you may have the buoyancy to still keep the deck above waterline in that scenario
I personally believe we need something more than air chambers under our decks, is foam the best option? well I think there are better ones, but its still a viable one, and defiantly better than nothing at all. If all its there for is to keep the hull afloat if rolled over, then its a waste of time, buy a life raft. Even by putting the foam higher up will achieve nothing in my thoughts, I can't see how you will ever get enough of it to be practical and buy the time water reaches it do anything its too late anyway.
Cheers
Katoh
I maybe slow, but I'm bloody rough!
Katoh
I maybe slow, but I'm bloody rough!
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THEMOORINGMAN
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Re: Foam OR No Foam?
This is so true and I'm glad you wrote it. "If you're going to put flotation in, the bottom of the hull is the absolute worst place to put it."
I have sealed compartments but what happens when I really get in trouble and go bottom up with bilge pumps in each compartment........SUNK! I often thought about shut off valves to trap the air.
Solution= Carry an inflatable liferaft especially in COLD water!
I have sealed compartments but what happens when I really get in trouble and go bottom up with bilge pumps in each compartment........SUNK! I often thought about shut off valves to trap the air.
Solution= Carry an inflatable liferaft especially in COLD water!
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welder
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Re: Foam OR No Foam?
Challenge wrote:Ok guys, I read through this link and also did a search and I could not find out how/what type of foam Pacific uses "below decks" sorry if I missed it!
Cheers
Rick
Rick you probably wont and they wont tell you how it's installed , how it drains or any of that trade secrete stuff.
Again, if the right foam is used and installed correctly there are no issues.
Pacific will sell you a boat with NO FOAM in it , no problem, it's the customers call.
Lester,
PacificV2325, Honda BF225
2386
PacificV2325, Honda BF225
2386
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kmorin
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Re: Foam OR No Foam?
I think the CG/DOT/HLS reg.s call for level flotation in boats shorter than 20' LOA? I may be mistaken as I do know I have not read the reg.s for some time but they did require all 'voids' to be flooded in a float test and that implied something inside these tanks/voids/spaces had to displace water so the boat would remain at the surface.
But, if this regulation applies below 20's I'm fairly sure it does not apply to boats longer than 20' at least that is my understanding.
Aluminum boats' main seam welds should be continuous and sealed unlike the interior structural 'stitches' which may be installed a few inches each foot to attain a structural only function; not to seal the hull or decks. Depending on the design, the main hull welds are generally two sided- inside and outside full length welds. Decks are often only welded on top, where the decks meet the topsides. Regardless of weld design and prep, that deck weld should be tested to insure water tight deck-to-bilge seal and an air test is the most reliable means of testing this weld.
A few PSI (not more) of air inside the skiff bottom will reveal leaks in the deck weld and they can be "TIG floated" closed so the boat's bilge is truly sealed from deck water.
If we go to the effort to air test, why add foam, either before or after adding the deck? Its added wt, it costs something to put in, and it may if not done correctly cause or at least support corrosion in the bilge.
Why put air/flotation below the decks? Most welded power boats will not be in a 'Perfect Storm' breaking sea -ever. In a perfect storm breaking sea the boat is filled in one or two waves descending into the skiff's deck and filling her in a very short time. If the boat fills in a very short time, a few seconds or one minute, then the buoyancy under the deck may roll the skiff keel up, but that is not the usual case.
In my experience in the Gulf of AK, I've seen weather get a little lumpy and I've seen some spray and perhaps the top of a wave clipped into a skiff when the weather did get rough. If the water coming aboard is not instantaneous, or nearly so, then the flotation under the deck lifts the deck over and over, and the water is lost out the deck scuppers or freeing ports. So, for 99% of the boat's life I see air under the decks as helpful and valid and unless the topsides were nearly double walled/double hulled; the fully swamped boat will be rolled over in the same seas that would instantaneously fill her. In fact, with the hull filled but floating due to sidewall voids, the skiff would still be swept by each sea and while it may remain at the surface I'm not sure I see a clear difference in safety from clinging to a upside down swept hull and a righted swept hull? (I'm not discussing boats with a cabin; my remarks are about open deck or console and walkaround boats.)
I'm still not a "foam believer" because it only comes into 'use' when the boat is holed, then filled, and I've yet to find that to happen. We've read of the work boat getting holed, but also read of the sand filled skiff that was literally rolled up on the beach in the surf- both ends of a fairly tough spectrum of endurance.
So I can't buy into foam, but like painting alloy boats, it can be done, works if done right, and some folks prefer color over the metal's finish. If foam makes a skipper feel good, then it seems worth their money to buy it; but like paint, its not needed.
Cheers,
Kevin Morin
But, if this regulation applies below 20's I'm fairly sure it does not apply to boats longer than 20' at least that is my understanding.
Aluminum boats' main seam welds should be continuous and sealed unlike the interior structural 'stitches' which may be installed a few inches each foot to attain a structural only function; not to seal the hull or decks. Depending on the design, the main hull welds are generally two sided- inside and outside full length welds. Decks are often only welded on top, where the decks meet the topsides. Regardless of weld design and prep, that deck weld should be tested to insure water tight deck-to-bilge seal and an air test is the most reliable means of testing this weld.
A few PSI (not more) of air inside the skiff bottom will reveal leaks in the deck weld and they can be "TIG floated" closed so the boat's bilge is truly sealed from deck water.
If we go to the effort to air test, why add foam, either before or after adding the deck? Its added wt, it costs something to put in, and it may if not done correctly cause or at least support corrosion in the bilge.
Why put air/flotation below the decks? Most welded power boats will not be in a 'Perfect Storm' breaking sea -ever. In a perfect storm breaking sea the boat is filled in one or two waves descending into the skiff's deck and filling her in a very short time. If the boat fills in a very short time, a few seconds or one minute, then the buoyancy under the deck may roll the skiff keel up, but that is not the usual case.
In my experience in the Gulf of AK, I've seen weather get a little lumpy and I've seen some spray and perhaps the top of a wave clipped into a skiff when the weather did get rough. If the water coming aboard is not instantaneous, or nearly so, then the flotation under the deck lifts the deck over and over, and the water is lost out the deck scuppers or freeing ports. So, for 99% of the boat's life I see air under the decks as helpful and valid and unless the topsides were nearly double walled/double hulled; the fully swamped boat will be rolled over in the same seas that would instantaneously fill her. In fact, with the hull filled but floating due to sidewall voids, the skiff would still be swept by each sea and while it may remain at the surface I'm not sure I see a clear difference in safety from clinging to a upside down swept hull and a righted swept hull? (I'm not discussing boats with a cabin; my remarks are about open deck or console and walkaround boats.)
I'm still not a "foam believer" because it only comes into 'use' when the boat is holed, then filled, and I've yet to find that to happen. We've read of the work boat getting holed, but also read of the sand filled skiff that was literally rolled up on the beach in the surf- both ends of a fairly tough spectrum of endurance.
So I can't buy into foam, but like painting alloy boats, it can be done, works if done right, and some folks prefer color over the metal's finish. If foam makes a skipper feel good, then it seems worth their money to buy it; but like paint, its not needed.
Cheers,
Kevin Morin
kmorin