1971 Silverline Comoro 16.5

[Scott Danforth]

There were a few powerglides in front of a standard outdrive boats many many years ago. The motor was midships

One of the large Volvo dealer also has a 2 speed drive where the mid section of the drive has a hydraulically shifted under drive to get large boats moving

Multi speed transmissions take up way too much real estate within a boat. The juice isn't worth the squeeze

But you won't ever get the prop spinning fast enough for it to explode...... Ever. Especially with only a small block...... I mean ever. Even if you strapped blowers and turbos. My bosses boss currently holds the record at lake Havasu for the fastest V-hull, spinning two 3500-4000hp motors at nearly 10,000 RPM (6660 RPM prop speed). These motors started out as Mercruiser 1650s (Twin turbo and supercharged 9 liter racing engine)..He was set to break his last record when one of the motors left the chat when the pistons wanted to play peekaboo there have also been turbine powered prop boats where the prop was spinning more then 10000 rpm

 

[MikeSchinlaub]

I would glass the whole stringer and floor back in. You have to fill all those cavities with floatation foam once the floor is back in, so the stringers will be covered all the way up the sides. The floor is also structural, and should be glassed all around the hull like it was.

I also think you're over thinking the frame. My supervisor is a bit over 6' and 200lbs, and the floors hold him up just fine.

If you do a good job, this is going to last you 20+ years.

 

[Scott Danforth]

I agree with Mike, dont overthink the stringers.

I personally would use 3/4" plywood and round over the ends with a router. no need to make it heavier by using dimensional lumber. if you want 1", just laminate 2 sheets of 1/2" together with titebond III

I have laminated plywood using both PB and titebond III when it comes to the transom. using a plastic tile trowel to spread it, goober one sheet, lay on the other, then with a box of drywall screws, starting in the middle, just tie them together. the next day, remove the screws, and cut the plywood to shape.

 

[Wrenchstench92]

Good morning guys. Ok I understand now, so the cavities between the stringers all get filled with floatation foam? I was under the impression that only a certain amount of foam was added because of how it looks now. There is only foam like 1 inch up from the hull (see pics). And the center cavity has no foam.

If you guys say that 3/4 plywood will be strong enough then that’s what I will do, it seems what was used originally was too weak and flimsy but maybe it’s an illusion because it’s all rotted.

I appreciate the input guys. I am going to start on the boat this weekend, first step is getting the motor out then I can start disassembly of the stringers. I will keep you guys updated.

 

[MikeSchinlaub]

3/4 would be fine for stringers, it just gives you a narrow area to hit with the screws. Hard enough to hit a 2x that's really only 1 1/2".

The foam you have is someone saying "screw it, good enough". Usually, the floor goes in, then a few holes are cut along each cavity and expansion foam poured through. It's supposed to expand up to the floor. The empty center could have been for a ski locker, or just drainage.

 

[Wrenchstench92]

3/4 would be fine for stringers, it just gives you a narrow area to hit with the screws. Hard enough to hit a 2x that's really only 1 1/2".

The foam you have is someone saying "screw it, good enough". Usually, the floor goes in, then a few holes are cut along each cavity and expansion foam poured through. It's supposed to expand up to the floor. The empty center could have been for a ski locker, or just drainage.

Yeah that’s what I figured, I read one of the posts of the user friscoboater of his restoration and he mentioned like you said, cut holes int the cavities and fill till its full.

So in the center, could I use that as a ski locker? Or is it better to fill with foam? It would be nice to use as a place to store a cooler, or a live well for bait/ fish. I would make a flat platform between the center stringers, and that would double as a floor for the storage and add structural integrity, and I could do the same as the deck, cut a few holes and fill under the platform.