Internal Bracing

[paddler]

I'm sure this has been discussed before, so I'm looking for a discussion regarding the different types of internal construction for hulls. Pollard's book states that longitudinal bracing is the strongest and makes the argument that thicker skin material saves labor costs vs using a thinner skin with more internal bracing. The best example of the latter I know of is Wooldridge. Looking at photos of their builds looks very labor intensive, and makes me wonder whether all that internal bracing actually yields a hull much lighter than those built with thicker skins but less internal bracing? A couple of points in favor of the former is larger spaces under the deck for storage and better resistance to hull penetration in the event of striking a submerged object. Can anybody point me to a good resource on this topic?

[Napa Mike]

I think you might be getting lost in the forest, Paddler. Sometimes the perfect is the enemy of the good. Go get something that suits your needs.

Mike

[kmorin]

paddler,
Dave Gerr, a ring frame advocate, has some discussions in older issues of the Boat Builder mag, not sure if that's in print? His book Boat Strength also addresses this design element and there is a current discussion on the boatdesign.net under Design about metal framing comparisons. Pollard's Guide to Aluminum Boatbuilding is just a guide making huge sweeping generalizations, not to be confused with a design by design comparison of boats!!

Essentially the issue is not one way or the other, it is a balance between one end of spectrum (Strong All) and aircraft modeling of framing with thinnest skin possible. So without setting prior goals in order of design criteria, you can't begin to compare the various builders' solutions- if wt is important then what is the reason? If impact is critical what wt will be given up to get that? The idea that one can make the statement of 'best' in this category of engineering balance is not informed- no designer can make the decisions needed to balance the various framing methods without the goals to weigh the choices.

Glen's boats are not more or less labor intensive since the framing is pre-cut, bent and prepared for each model's bottom. If these elements were hand laid out, cut and then fit and tacked I'll agree that labor may be a factor; but then we pay for labor or pay for metal and forming? There's not that large a spread in cost if you use the boat class to group the designers and builders instead of allowing all boats without regard class, into a comparison.

What you're attempting is a non-trivial exercise. I'd say that making a table of LOA, BOA, depth keel to sheer and then listing frame elements and other scantlings with framing centers and all up welded wt- would be about the only way to get useful information out of the builder's various brochures and online info.

Cheers,
Kevin Morin

[paddler]

I think you might be getting lost in the forest, Paddler. Sometimes the perfect is the enemy of the good. Go get something that suits your needs.

Mike

If I'm going to spend $100K(+?), I like to have a better understanding of boat structural design. Don't want to rush in and regret not having thought about everything. Even though my Hewes isn't the boat of my dreams, it fishes well enough that I can take my time. I just want the lightest boat within reason, given my intended use. It seems like having fewer transverse bulkheads below deck allows for larger storage areas, which prompted my question.

I like the lines of Specmar's hull #1147. The sheer is to my liking, and with a couple of small changes, it could serve me well. Has anyone seen this design in the flesh? It's a pretty popular size, and there are a number of similar designs. Waiting to hear back from Bruce Cope, but it's been a little bit. I spoke with Doug at NWAC, he's quite busy and doesn't sound excited about my project.

[jj225]

The problem with Specmar is that there aren't a lot of boats out there even if it's a "popular" design. I had some lengthy email exchanges with them and talked to a few builders about some of the boats that have been built. Just not a lot of confidence in a design when there's maybe 2-3 out there in the one you like. Same with Cope.

I actually was going to go with a 22' boat built by Doug at NWAC. Loved the lines and built like a tank. Every owner I talked to LOVED their boat and had nothing but great things to say about it. Very different from a Woolie in terms of weight and motor requirements though. In the end the guy was hard to deal with. Wouldn't answer emails and was literally NO HELP when it came to getting the motor and electronics mounted. He said all he wants to do is build the boat and get it out. He wouldn't even rig the motor. Now that doesn't sit well spending 10's of thousands on a boat and taking it home w/out ever being able to test ride it. ZERO help in dealing with the issue of Canadian motor vs. US motor and getting the boat thru customs. When I tried to schedule a trip up he said he was busy with the "commercial opener". Never did explain how that would impact his boat building. Then there was the issue of a loan. Very hard to get a loan from a shop most lenders have never heard of PLUS it's in Canada. None of the lenders I talked to would do it for a non production boat that was built there. If I lived in Port Angeles I may have over looked some things but not with me being in CA and you Paddler aren't much better off in UT. Logistics are a beeitch. You can say the same with Wooldridge but here's the big difference; they excel at customer service. When you have issues BEFORE you even put down a deposit with a builder it makes one think very hard about moving forward.

[paddler]

The problem with Specmar is that there aren't a lot of boats out there even if it's a "popular" design. I had some lengthy email exchanges with them and talked to a few builders about some of the boats that have been built. Just not a lot of confidence in a design when there's maybe 2-3 out there in the one you like. Same with Cope.

I actually was going to go with a 22' boat built by Doug at NWAC. Loved the lines and built like a tank. Every owner I talked to LOVED their boat and had nothing but great things to say about it. Very different from a Woolie in terms of weight and motor requirements though. In the end the guy was hard to deal with. Wouldn't answer emails and was literally NO HELP when it came to getting the motor and electronics mounted. He said all he wants to do is build the boat and get it out. He wouldn't even rig the motor. Now that doesn't sit well spending 10's of thousands on a boat and taking it home w/out ever being able to test ride it. ZERO help in dealing with the issue of Canadian motor vs. US motor and getting the boat thru customs. When I tried to schedule a trip up he said he was busy with the "commercial opener". Never did explain how that would impact his boat building. Then there was the issue of a loan. Very hard to get a loan from a shop most lenders have never heard of PLUS it's in Canada. None of the lenders I talked to would do it for a non production boat that was built there. If I lived in Port Angeles I may have over looked some things but not with me being in CA and you Paddler aren't much better off in UT. Logistics are a beeitch. You can say the same with Wooldridge but here's the big difference; they excel at customer service. When you have issues BEFORE you even put down a deposit with a builder it makes one think very hard about moving forward.

Doug seems like a nice enough guy, but it's just him and another two guys at NWAC. He told me in his last email that he'd be no help with customs, just like he told you. Guess he has plenty of work.

Buying from a larger volume builder like Wooldridge should yield better resale just due to name recognition. I just can't get by the bracket thing and don't like the sheer line on their boats. My choice is either a splashwell design from NR, etc, which are not pilothouse designs, or semi custom. I'm not worried about resale so much, and don't need to finance, so those are factors in my favor. There must be a builder out there I can work with. Not too worried, just a lot to think about.

[jj225]

The boat with Doug was not going to be custom. Just his standard design. Yeah he is/was busy but he would have been able to start the boat within a few weeks of my visit. If it would have taken place. So being busy wasn't an issue more not being helpful was the problem.

Not saying you should go with a Woolie. To each his own. I have no doubt there are plenty on this board that would not. Funny thing I initially ruled them out. It wasn't until I started talking to a lot of owners via different forums ( over the phone not email) that I took another look at them.

Best of luck with your search. It's tough and really I don't think a lot of fun.

[Napa Mike]

I think you might be getting lost in the forest, Paddler. Sometimes the perfect is the enemy of the good. Go get something that suits your needs.

Mike

If I'm going to spend $100K(+?), I like to have a better understanding of boat structural design. Don't want to rush in and regret not having thought about everything. Even though my Hewes isn't the boat of my dreams, it fishes well enough that I can take my time. I just want the lightest boat within reason, given my intended use. It seems like having fewer transverse bulkheads below deck allows for larger storage areas, which prompted my question.

I like the lines of Specmar's hull #1147. The sheer is to my liking, and with a couple of small changes, it could serve me well. Has anyone seen this design in the flesh? It's a pretty popular size, and there are a number of similar designs. Waiting to hear back from Bruce Cope, but it's been a little bit. I spoke with Doug at NWAC, he's quite busy and doesn't sound excited about my project.

I hear you. It is just that you will find good boats and bad boats built either way (thin skin heavy framing and thick skin lighter framing). there is no inherently superior design. each boat stands on its own merits. Good luck.

Mike

[glen wooldridge]

paddler wrote:Glen, in the brochure of the 26' SS pilothouse with the fishing machine and pilot packages, the weight totals ~4400#. With the bracket, the LOA is ~28'3", correct? North River lists their 26' OS at 5500#. Can you explain the 1100# weight difference? I like that you build your smaller boats with .190"/.160" material, and wish other builders did the same.

In response to your question on Wooldridge Boats Pilothouse’s Under Construction, I will answer here.

Yes, our Pilothouse’s have offshore brackets, but the bracket is not included in the length, so yes, the overall length is over 28'.
There are a lot of different thoughts on construction. Here are some of mine.
We try to keep weight down. It’s easy to build a strong boat, but It’s harder to build a strong boat that's light.
It takes more welding and structure to keep a boat light. Labor costs more than aluminum.
You have seen how we use channels and rails in the bottom of our pilots for support. There are two
basic things in bottom strength. #1 is how thick or heavy is the bottom. #2 is what’s supporting or
backing up the bottom. Many boats are built using what is called box girder construction. Box girder is a
large formed channel. One of these supports each side of the bottom. It’s much easier and faster to
build a boat this way, but it only has 2 points of support per bottom side and thus, you need a heavier
bottom for strength. This is one place we save some weight. I believe we also save some weight in the
roof of the cabin, as we do a lot of forming and have a crown in the roof which adds lots of strength. Glen

[paddler]

Thanks, Glen. I think you're on the right track. One of the main advantages of aluminum cited by boat builders is it's light weight compared to 'glass. Yet it seems most builders don't take maximum advantage of this property to produce strong, lightweight hulls. An overbuilt hull is just that, too heavy for it's intended use and the far stronger than it needs to be in order to withstand the stresses to which it will be subjected. Given two hulls identical in shape, except that one is 20% lighter than the other, it seems the lighter boat will have a higher carrying capacity, be easier to tow, more fuel efficient, etc, etc. The best hulls can only be produced by combining to best choice of materials and the best engineering. You pay once for the additional labor involved, but you continue paying for the extra weight every time you trailer your boat or fill it's tank.

I noticed the forming on your roofs, kind of corrugations to increase rigidity. Clever.