Floatation Foam for my C-16?

[Pacman]

I am thinking about putting sheets of foam in the quarterberths and in the forepeak to make my boat unsinkable.  If I used luan plywood to hold the sheets in place there could still be room for the porta-potty and some storage in the main "cabin".

Question is:  Would this work?  How much foam would I need to keep my boat afloat?

If it would work I think it would be a good trade off (space for safety).

[GeeW]

The volume you'd need to make it unsinkable will be a lot more than the space under the bunks and forepeak.
From memory, For air you'd need circa 50 cu ft as an absolute minimum to keep it from going under.
Gordon

[MHardy]

Pacman,

I'm a 16 sailor as well. Just wondering what specific concerns you have that make you want to do this.

[bwhelton]

I did that when I first got the boat and it pretty much took up the forepeak and under the bunks .  The question is how high do you want the boat to float.  I had a bunch of 4" thick sheets of 4 x8 blue Styrofoam leftover on a job site  so I added about 25 cubic feet, just enough so I would have the boat floating with me if I ever sprung a significant leak a few miles out.  But as my confidence in the boat grew I got rid of it.

A lot of floatation Styrofoam sites have calculators on them

Brian

[wes]

A CP 19 weighs 2000 lbs. not counting motor and cargo. Water weighs 62 lbs. per cubic foot. So to make a 19 unsinkable you would need about 32 cubic feet of foam. That's the equivalent of a solid block bigger than 3' on each side.

For this reason, you'd have a hard time finding any keelboat that's unsinkable. Much easier with a powerboat - no heavy keel!

Wes

[Pacman]

Pacman,

I'm a 16 sailor as well. Just wondering what specific concerns you have that make you want to do this.

I plan to sail on some glacial lakes in Northern Minnesota where I have seen uncharted rocks just below the surface.

If I put a big hole in the boat I would want it to "float" high enough so I would be able to stay with the boat until help arrives.

[kickingbug1]

    the 16 is a rather "tender" boat in that it will heel pretty fast before it hardens up. with its small sail area i doubt it would get knocked down if the skipper was paying attention. in heavy wind have the mainsheet in hand and keep the hatch board in and buttoned up. as to  making the boat unsinkable, i dont think it is practical. couple that 450lbs of concrete with a cabin full of water, shes gonna go down.

[Pete H]

Hi Guys,

This was discussed in the Legacy section some time ago but should be easy to find. Calculations and formula for how much foam was needed are posted there. The amount of extra foam needed in a 16 would actually be fairly minimal I expect. In the Legacy, which seems to me to be basically just an updated 16, there is enough foam put in during construction to float it if holed, probably. The factory think this but can't say it as testing it requires them to sink a boat or some other equally destructive test.
Cheers,

[Pacman]

Pete,

Thanks for that thread.  It contains the formulas needed to calculate floatation and other good information. 

Based on the information in that thread I can see that the big foam blocks I had planned for the quarterberths will float the boat nicely. 

[relamb]

When I had a CP16 and a CP23 and went offshore, I carried an inflatable water ski tube as a "liferaft".  Inflate it ahead of time and keep it in the cabin.  It won't float the boat, but it will float a couple of people.   it also happened to be bright fluorescent pink which would be easy to see.  That, and a handheld waterproof VHF radio were my emergency bailout gear if it ever came to that.    I never tried tubing behind the 16, but my CP23 pulled the kids just fine!

[Duckie]

The glacial lakes in northern Minnesota are generally pretty shallow except for some, but in the deep parts you will not be able to hit anything that would hole your boat.  I have sailed the most northerly of them with my weekender and can report that for the most part the dangerous reefs and rocks are well marked both on the water and on the charts.  I also contemplated floatation for my 16 mostly because I would like to use it on Lake Superior when the water is dangerously cold.  Not that it isn't cold year round, but in the spring is when I would like to at least day sail on the big lake.  I think you could add enough floatation to keep it off the bottom, and if you figure out how to stuff all you gear in around the foam, I don't see why you shouldn't do it.  Especially if it gives you peace of mind.

Al

[tmw]

I wonder if you could fill in the bunks with air rafts (e.g. like pool rafts) and if that would provide the flotation required.  I have thought of using such an air raft.  1500 lbs would be 680 liters, which would mean 340 empty 2 liter bottles.

I agree that for my sailing it wouldn't be worth it.

[Potcake boy]

Sorry, 2 liter bottles sounds a little mundane to me. You'll need a little more imagination to make a real splash. How about beer cans instead? If you scout around some pickup beds you should find more than enough empties. I'd fasten them all along the inside of the hull and claim it to be your beer can collection, and no one would be the wiser, except that they would need to be upside down. Don't forget that if you are sinking to hurry and finish off the last full six-pack to add to the flotation total.

You know, I always thought an ejectable keel could be a real good idea.

Seriously, I wouldn't lie awake at night worrying about that. I'm not sure the sixteen would have enough speed or weight to do much more than bounce off of an underwater object. There is a lot of experience on this forum, and I've never heard mention of a 16 sinking from being holed while sailing. If anyone has, please share the details to make a judgement if it is a real concern or not.

[NateD]

I'm not sure the sixteen would have enough speed or weight to do much more than bounce off of an underwater object.

I hit a stump (I think) underwater at about 4-5 mph while motoring. Stopped the boat dead. Small chip out of the keel. A rock to the waterline might do a little more damage, but I think you're probably right, unlikely that you'll produce a significant hole in the boat unless you wash up on a rocky shore and get beaten by waves. I could envision a crack that seeps some water, but these hulls are pretty thick.

I cruise on Superior with my 16 without added floatation, and I'm planning to cruise for a couple days on Lake Kabetogama (one of those N. MN glacial lakes) this fall without added floatation.

If you're still paranoid I think pulling a small inflatable or a small kayak would be better than taking up precious cabin space with foam. Then you would have a way to get to shore easily too.

[Pacman]

I think pulling a small inflatable or a small kayak would be better than taking up precious cabin space with foam. Then you would have a way to get to shore easily too.

Good plan!

Thanks