UK’s 78 SN

Roger - I think you are onto something - waterproof foam!     It satifies both sides of the foam/no foam discussion (although what will we argue about next year?)    You should patent this.      Maybe there is a way to seal the seam using a process similar to the food-saver storage bag sealers? Maybe the foam could just be painted with bed liner or similar waterproof emulsion.

Correct crafts have a large amount of foam in the upper cap that never even touches water in sinking conditions.I would be willing to bet you can take the foam out of the floor and still not sink the boat.

Of course if you think about it air is more bouyant than foam and creating a trapping system in the hull is the most effective solution.
Does anybody know how they build the new boats?

Or you could cap a series of tubes and fill in the blank spaces with foam.Then seal the whole package.

Ryan tubes would do the job, maybe the flexi type that can bend back and forth so only 2 ends to block off then fill with foam in the Pvc and wrap for a sheet floor or coat for a lay up floor, looking good.

Just did the weight of the block after 24 hours in water and looks like the skin on foam is much better at stopping water soaking in now @ 193.4g think some of the gain is due to loss of the skin when I took it out the mould if you look a picture you can see.

At the moment its added by 2.4g   (0.084657)oz now back in the water,next weight after a week.

Ryan that's a good call on the old foam as you said I still have some up under the bow, will try and cut some out with the skin on to test how much it soaks up and buoyancy, as for epoxy tubes yes would work too, brings us full circle as I have the 2 epoxy ballast tanks, if I get the pluming right will work as buoyancy when not in use, as for how much buoyancy they make will need to try and work out, now you got me scratching my head.

If others know how here are some stats each      Tank weight dry             35 lb
                                                                       Tank full of water           201 lb

This is what I have found so far with my 78 SN using the numbers on a standard boat just the hull should be around 553.2 lb just unsure if the weight given in reference include platform and back seat? if not need to add back onto hull weight, feel free to add of amend would be great to get actual weight of an complete engine and drive as the one I have is off the net and my scales won't go that high.

UK's 78 SN          weight lb
Ref boat weight 2100 lb          
350 engine and drive 1:23:1          950 lb
Wood stringers Dug                  136 lb
Ply wood                          40 lb
Fiber glass stringers                  241.5 lb
Ballast tanks                         70 lb
Foam used new type                  3.368 lb/3
Vortec heads complete 2 off          86.20 lb
Strut                                  3.8 lb
Prop and shaft                          16.1 lb
Pylon                                  21.3 lb
Rudder & port                          21.4 lb
Floor seat mounts                  5.6 lb
Platform brackets                   7 lb
Front lifting ring set & pull          6.4 lb
Back lifting ring set                  4.6 lb
Exhaust ports                         3.16 lb
Exhaust silencers & pipes          29.6 lb
Back floor ply and tank support          26.4 lb
Extract fan and pipe                  1.6 lb
Side pockets in ply and wood 2 off     38.4 lb
Fuel separator                          1.8 lb
Battery 110 amp                  61.2 lb
Driver seat                          23.6 lb
Passengers seat                          29.6 lb
Back seat covers                  13.6 lb
Dog house with extinguisher          72 lb
PCM 1.23.1 dry                          68 lb
Velvet Drive dry ish                  95 lb
Engine mounts 4 off Chevy          48 lb
Engine mounts 4 off Ford          51.6 lb
My Guess on all wire and cables          15 lb
My Guess on helm, gages, throttle     21 lb
Back seat frame                   18.2 lb
Gas Tank                         20.8 lb
Teak platform                          18.6 lb
Windscreen                          34.2 lb
Ski mirror                          3 lb
Air guides and mount panel          3.6 lb
Steering wheel 14in                  4.6 lb
Tracking fins 2off                  8.2 lb
Edelbrock manifolds 2off          25.2 lb
My guess on all scews,rubber bump          
rail,log,ally trim & fittings          32 lb
Carpet                                   16.6 lb
Standard Hull with stringers works out           
at                                   553.2 lb

Here are my findings on the foams.



Foam with a cut face 2 wk underwater   now 61.7g   has 15g of water soaked in.

Foam block with skin 1 wk underwater now 196.9g has 5.9g of water soaked in.

Foam like pool noodles 1 wk underwater now 14.2    has 3.2g of water.

Thanks Eric will update my spred sheet now back to my specific gravity tables.

Done my attempt on working out floatation on a 70s SN came up with 20 cubic feet of the foam I'm using, think it would be around the same for a Ford boat
Interesting to find how much flotation there is built in the boat, wood stringer system is worth 115.85 lb and the total for the boat without foam 219.92lb
I have tried to post my excel spread sheet with no joy so put it in word still no luck! if someone know how to please let me know and will post and Easy on the red pen all you engineers out there.

Someone already tried.......... but not a scientific study!!

Did these a year or so ago, may be of help to others and could help keep the average age of boats here down

Sorry but sizes are mm







Sizes taken off my old stringers at the wide side of each,always check your ones are the same if you use the above drawings on your project.

Have Cad file if you need to print full size for template.

WOW! That original foam took on some serious numbers! What a cool project!

Roger, excellent source of information, more reasons to solidify the foam issue, and its one of those issues that is mandated by the powers to be but the end result is not positive. to date we have one positive reason for foam and that is flotation, but you took on the task and once again turned the issue into another negative. Foam is put in these boats to satisfy the USCG, but with extensive testing and time we can see the many negatives of the foam, you really have to sit down and reason why or why not you would want to re-foam your boat if you plan an extensive rebuild on it. the foam does provide short term flotation, but after time does it become a safety issue and possibly weigh the boat down and increase the chance of it sinking with the saturation of water and being a catylyst for rot does this create safety issues?

Thanks Chris,Chris,Eric,Ryan a few things have crossed my mind with this little test, if you look at the top of the foam block its sunk quite a bit, its been in cold water and that may of effected it ! also those of us in the cold parts of the world could the freezing of water in the new and old foam brake down the closed cells each year so in the spring the foam is ready to soak up more water?

So:
New foam cut approx 50% weight gain
New foam uncut 4% gain
Noodles 50% gain
Original (I assume open cell) 100%+ gain

I know which one I would use!
Interesting thought about freezing.

I wonder if freezing for an extended period would dry the foam back out - you know how old ice shrinks from solid evaporation? (or whatever the phenomena is called). Maye one of the Northwoods guys might have to set up that part of the test! Okie - got any old foam leftover?

If i may chime in her after numerous test and still many other mitagating factors left to resolve, cold ,heat ,freezing , why not just eliminate the foam ?. like Erick said the boat companys do it because its mandated by the USCG. most of have enough life vest and ski vest to keep our boats afloat.