hoodoo

The builder that helped me convert an early eighties Hawk 40 into a center console glassed the deck on without foaming the stringers. The stringers are massive and boat is rock solid but I want to fill them with 5lb foam. The stringers are about 4" wide at the top are easily located but are bonded to the deck with arjay putty, can I get a holesaw though this stuff? I've heard it is really tough to drill through or should I just foam in all the cavities between the stringers,bulkheads and leave it at that?

glassdave

iTrader: (1)

why 5lb? Generally 2lb is what is used. By the looks of it that thing is gonna be heavy, thats some stout scantling there. Not sure I would even put foam back in If it were mine but if I did it would be the lightest I could get. keep in mind 5lb is going to expand two and a half times less them 2lb so you will use far more and weigh two and a half times more for the same volume.

what did they use for the stringers core? wood or foam?

hoodoo

Glass stringers were pulled from a 3 1/2" by 30' mold and capped with two layers of carbon fiber.
The hull was completely gutted and ground down and relaminated with Kevlar and carbon fiber.
The boat weights 6110 # with all the console/ t top etc in it, before diesel power goes in.
Hoped to get out the door around 10,000 #. My worries were that the stringers should be filled to dampen the vibration, and add floatation. Another issue with filling the stringers is the 4" rigging tubes glassed in from the rear bulkhead to the well under the console, I considered drilling through them to get the foam in and then putting in sleeves, but that sounds like a big mess.

hoodoo

stringers are very stout but completely hollow
I hear ya on the 2# vs 5 #

glassdave

iTrader: (1)

oops, i kinda misunderstood, for some reason i thought you meant the voids under all the decking even though you clearly said stringers lol. Well, I'm not so sure you'll gain anything by filling other then weight although i suppose there will be some level of dampening but as beefy as they look you might not notice. I would also be very careful if you do decide to fill with foam. Usually large cavities like these are done in production with a special gun that allows a fair amount of control. Using a mix and pour method it will be difficult to meter it in just right so that the fill is consistent and even throughout. Mix the wrong amount and have it dam up and your likely to blow the stringer apart (I've done it, that stuff can generate some PSI if your not careful). Margin call i guess . . . .

hoodoo

I'm just foaming the voids, getting it into the stringers is going to be too risky or require an azzload of holes in the deck and stringers without gaining any real structural advantage .
Thanks for your opinion

sparky24

cool project man what are you powering it with

hoodoo

Supposed to be getting 550 Duramax's from Innovation this winter.
Their test boat (older 42 fountain 10,000#) runs 55 mph with a single and a buried #6
Looking for 70-75 mph with a pair

hoodoo

Its actually a Chris Craft 39 Scorpion but that's too much to type, they came from the Bill Farmer mold.
I really hated to chop it up but was committed to a diesel CC project and the stringers were rotten but the lamination was surprisingly good.
It was a staggered setup with ssm 3's before someone parted it out.