Self righting aluminum boat ?

[zurk]

I was thinking about adding one 550lbs positive flotation bag to my radar arch below the radar bolted in place. http://www.amronintl.com/subsalve-enclo ... 0-lbs.html is cheap enough at $300.
Add two more at the sides and I will have about 1500lbs of positive flotation for a 2000lb boat fully loaded in addition to the level foam flotation. Wondering if that would give me the ability to have the hull self right ? or is it overkill ?

[kmorin]

Zurk, first since we're not, at least I'm not, familiar with the boat most of the questions are little bit hard to field.

So, my questions may seem off point, please let me know if I missed something?

Wondering if that would give me the ability to have the hull self right ?

Self righting implies a boat filled to the gunwales, and rolled over. So you've taken a 2,000 lb skiff (open?) out where you're serious concerned with being filled, rolled and then want to consider self righting? My first remark is don't go. I'm not saying there is no discussion to be had about safe boating and catastrophic flooding, but a skiff so small that hull, propulsion and full crew with gear only weighs (short) tonne? I'm sort of stopped by the design use of that small a boat in rollover conditions.

For example a 20' skiff (600lb.- 800lb.) with a 60hp engine (300-400 lb.) two (my sized ) guys (400 to 500 lb.) and gear ( 100 to 200 lb.) with fuel (50-250 lb.) will push 2,000 lb.- and I don't think its a reasonable idea to rig that size skiff for eventual roll over and self righting conditions?

With all that said, the two bags at the gunwale will right the skiff as the mass of the topsides downward to the keel will be unstable at the surface when inverted, so the bags will be sufficient to keep her floating up right, awash at the flooded sheer line.

If you have a boat designed with level flotation, that implies she will sit about level when flooded/swamped so... a bag half as large as you propose at each gunwale will keep her floating, even flooded, keel down.

If you'd like to have her really safe? have the bag making company build you a set of bags, that are contoured to your skiff's topsides sheer. Then have the bags collapsed with vacuum pump and rolled to fit into Velcro lanyards under your sheer on the skiff. Then use a 4500 psi 'paint ball' airgun canister to inflate this 'shaped life vest' either with a salt water trigger (dissolving pellet) or by hand. Either way, the air deployed into this shaped bag will instantly make your skiff into a RIB and you're "safe", if the EPRIB/Sat Phone/Cell or hand held are still working?

Cheers,
(and be safe)
Kevin Morin
Kenai, AK

[zurk]

i was thinking more of a situation like this : http://youtu.be/nrmD0WxtJAc?t=2m
calm sunny day - no waves - 3 ft of water - then BAM! boat is toast.

These guys make something like that : http://www.henshaw.co.uk/ribs/39-how-does-it-work but it takes 12 seconds minimum to inflate. 12 seconds underwater and the outboard is toast. on the other hand having a pillow with 500lbs of flotation on the radar arch i would think may right the boat faster ?

[kmorin]

Zurk, not that I know those folks, but clearly they're pukers. I mean leaving a skiff on the hook without knowing the inlet well enough to keep the RIB outside the rollers on the beach?? come on....! leaving a skiff without rigging a running line to be able to adjust for the swell, tide and beach bottom shoaling is just a demonstration of the lack of seamanship. Besides the anchor may have drug, as the bow was left to fight the rode, pulling up on a soft sand bottom- that hook can't hold well just from I can see in the video. Short scope, pitching bow snubbed regularly by the rode, lifting a short scope lay of the shank??? - I've beach moored skiffs lots larger than that one for nearly five decades without incident in a little bit bigger latitude and a whole lot bigger shore break than that.... and find that whole show embarrassing; not typical.

This RIB was stable in the inverted position because it has no top hamper or superstructure, and besides it was totally surrounding by flotation, so even if they'd had a float back on a mast (!!! ?) it wouldn't have righted the skiff as it rolled in the surf where the console was bottoming in the swelling (watch the jerking shaking motion as the skiff rises and falls.)

This was surf, are you saying this rig is planned to right you in the surf as you're washed onto a lee shore? Nope.. the bag will have no effect, I was assuming something more off shore, where you might get filled and rolled by larger waves off-shore then recover.

Inflation rate/time is the orifice Cv and the differential pressure ratio.

Sorry to misunderstand the situation, it would be interesting to see the RIB demo out of the harbor in a quarter mile out, beyond the surf in waves. Wonder if there is any video of the unit in 'real' use?

cheers,
Kevin Morin

[goatram]

Boat sinks I don't want it back. No Flotation in the Boat.

Get a liferaft. If you are concerned.

Wear your Gumby Suit instead of your vest for real protection from dock to dock.

Really worried? don't go?

My Opinion

[capesteve]

Pukers is a good way to put it. Just plain stupid

[goatram]

We need a Like Button on AAB

[welder]

We need a Like Button on AAB

This request has been sent to our IT guy, lets see what can be done with out crashing the site.

[Sabs28]

We need a Like Button on AAB

That is FUNNY.

[JETTYWOLF]

I seen that video.........who anchors a boat in what can ALWAYS be the SURF??????

You won't see anyone around here doing that!

That gals azz is the best thing in that video. Seen it before. Hmmmm, it looks good.