UK’s 78 SN

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.

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

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.

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.

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

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

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.

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

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?

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.

Roger,
Thanks for taking on the testing of foam. I think what we need to do is figure out a way to encapsulate the foam similar to the way they do the dock foam. I like your foam mold if there was only a way to heat shrink it to waterproof it. Monty

There you go Kris that's the amount of water the foam has taken on after a week! my thoughts are it will now level out but time will tell.
As for foam or something else against running nothing again is subjective to if water actually finds it way inside the hull in a big way and how well you do your floor stringer rebuild. Again some of this is down to how you intend to use your boat,for me I shall be in the sea as well,may even run over to France on a flat days its only 26 miles so the tanks and foam give me piece of mind out at sea.
The way I see it if you run with nothing and for some reason water is finding its way into the voids it will just fill up and hold more water unless its well air vented in some way and if you should take on a big wave could sink.
So if there is something under the floor that is buoyant there is less room for water to fill, now having played around with the modern foam and something Pete has said many moons ago will try another test on the foam.

Thanks for your input and just for fun popped a bit of packing foam which i think is like the pool noodles been under a day taken on 0.5g

    13.5g of water.

Checked the foam now after a week submerged now at 60.2g so has soaked up by 13.5g (0.48 oz) so still holding up well,now submerged for another week.

never, ever notice the stink?

After the first 24 hours under water took it out and dried the outside only,weight is now 56.3g so has soaked up by 9.60g or put on 0.34 of a ounce of water, the volume of the foam is around 22 cubic inches,now back under water to see if it will soak more.

So far its holding up well.