SailNet Community banner
  • SailNet is a forum community dedicated to Sailing enthusiasts. Come join the discussion about sailing, modifications, classifieds, troubleshooting, repairs, reviews, maintenance, and more!

Floatation!!!

3K views 14 replies 7 participants last post by  SJ34 
#1 ·
Hi there
I have a Crown 18.5 fiberglass swing keel trailer sailor I'm renovating
Basically a Mini Cal 20 with a swing keel
I'm tabbing in new ply bulkheads and quarterberths and I'm contemplating floatation foam while I'm at it
There's enough room front and back and under the quarterberths to accomodate the foam and still leave me storage space and I could balance it out pretty well too (about 9 cubic feet front and back and 6 under the quarterberths)
I can get a decent deal on enough to float my boat about $200 for 6 gallons, which gives me about 24 cubic feet = about 1,440 lbs of floatation (after subtracting actual foam weight)
This does however add 50lbs to the boat weight and $200 to my reno cost
I'd appreciate the added security of the foam as I hope to do some Gulf Islands cruising(protected waters)
I was wondering if there were any opnions on the practicality of this etc
Thanks
 
#2 ·
Yes, and it is a good idea in my opinion. I looked into this once in detail for my wooden boat. (all wooden boats are in some state of sinking).

Check out Larry Pardey's book "Cost concious cruiser". He has some good information on making your boat positively boyant.


Medsailor
 
#3 ·
Are you sure the boat doesn't already have flotation? If I recall correctly, all boats built in the United States after 1965 measuring 16 to 26 feet were required to have full, upright flotation. I could be wrong with this one, but I don't have time to search the Federal regs. You may be able to Google this one and find out. A lot of smaller boats, those ranging 10 to 16 feet, have foam blocks beneath their bench seats, and the boats that are double hulled usually are foam filled between the inner and outer shells.

Good Luck,

Gary :cool:
 
#4 ·
I'm sure there is no existing floatation
I've replaced 3 bulkheads and right now the quarterberths have been completely removed, the new ones have been made and are ready to install
So there aren't any closed spaces (except between the 3rd and 4th forward bulkhead sand that's not adequate to float the boat)
This isn't a double hulled boat nor does it have filled bench seats
It's a little pocket cruiser
Besides this boat was built here in Vancouver BC by the same people that were building the Cal boats here so it wouldn't be subject to US regulations
 
#6 ·
Funny!
My mutineer 15 dinghy has floatation and it's somewhat comforting to know that short of hitting a mine or being blown up somehow I'll likely stay afloat
I've heard that as the sailboat gets larger it stops being space effective because of the huge amount of floatation required
Any more opinions out there?
 
#7 ·
Several pros and cons for flotation but if your gonna do it why not use polystyrene? It's much lighter and cheaper than the expanding polyurethane foams. You could fill most of the voids with polystyrene blocks then make up the rest of the volume with the expanding foam. Just a thought.

50lbs at the ends of an 18' boat will contribute to pitching motion.
 
#14 ·
Regarding positive flotation in a smallmkeel boat - all the Schock Harbor 20s since approx. Hull 130 have foam flotation. We install 22 cubic feet of foam in a 1,800 disp. boat. We have a 6 ft bow tank.

It required a surprising amount of calculation and testing to get the location of the foam correct.

We found that one needs to be careful when cutting and inserting the foam to make certain to try and prevent the foam from chipping. Instead of a knife, we use a heated wire to cut the foam - it seals by melting the foam.

Also, select a foam that will not under any circumstance absorb water. We did extensive long term (30 & 60 day) immersion testing of closed cell foams and discovered some closed cell foams would absorb a minscule amount of water, this might lead to nasty molds and smells.

We heat shrink the foam blocks to seal them. We considered applying resin or gel coat as a sealant ( we have plenty of those materials around ), but decided on heat shrink wrapping the foam.

I agree that one should carefully consider wherenin the boat the foam is placed, ideally if the boat swamps it floats more are less level.

One should also consider the weight of the crew and the weight of the gear in the boat.

Finally, I think you might also consider glassing in air tanks with inspection ports similar to dinghies. If a DIY has enough experience, it should be easy enough to do.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top