Radon extension and rebuild project

[Bigtalljv]

Hi, I’m getting to the point where I’ll be putting the first new stringer in so I’m starting to plan. It will be a marine plywood core stringer.

My question here is foam padding vs bedding in thickened epoxy? Is one favorable over the other? Is it mostly builder preference?

Seems like both have pros and cons, it would be A LOT of thickened epoxy material but I hate thin layers and strips of stuff that the foam would be.

Any thoughts?

thanks
Jason

 

[ondarvr]

The only concern is not having the plywood contact the hull intermittently and create hard spots.

While this is best practice, 99% of smaller boats don't have the stringers bedded in anything. They lay the plywood stringer grid directly on the hull and rarely have a problem. So, whatever you do, it will be better than the original build.

Also, the thicker the hull the less of a concern it is.

 

[Bigtalljv]

Thanks!

my old boat actually had big balsa pads under the stringers so I guess they get better grades for a 70s boat builder

jason

 

[kapnD]

I wouldn’t bed the stringer in goop, that will create a continuous hard spot, same as setting the stringer directly on the hull.
Put a few chopsticks under the stringer to hold it a uniform height off the hull, then Use some low expanding spray foam between the stringer and hull, and if you’re careful, you can make your fillet with it too.
Be careful to sop up any excess resin that will pool on the high side.
I think the balsa pads were a brain fart, and it obviously was a wet one!

 

[Bigtalljv]

Well I kind of let this thread fall by the wayside. I have been busy on other threads in other places but I thought it was time for an update and my latest goof. So I was following the “put back what you found” method and had talked to several people with experience rebuilding these boats but there was a small detail that didn’t come out until it was too late, they don’t put the new stringers back where the old ones were….
I don’t think it’s a huge deal. The boat originally had four stringers, two main center ones for the engine to mount on (IO) and then two much smaller ones outboard of those. The current rebuilders who convert to outboards are just using two much larger stringers (LVL cores are popular) and they move them out 8 or 9 inches to divide the boat in thirds and skip the outer stringers. So I put my new stringers where the old ones were. The difference is about 4.5”. So I guess I’m gonna make some small outer stringers. I’m not sure if that’s and issue? It doesn’t affect layout much, fuel tanks can only be so big and there would never be enough space for in floor lockers at the edge, it’s room for wire and hose chases….
I’m not really asking for any opinions unless you can think of a catastrophic issue I don’t know about, mostly I’m recording this to perhaps help somebody else in the future. I saw pictures of the boats with the two new stringers but it just didn’t register, 4” is hard to see over 8’.

 

[Bigtalljv]

Well it looks like I haven’t been keeping this thread up to date.

so I have finished the hull extension and had a question:
Should I or do I need to extend the lifting strakes?

It looks like the strake lengths vary a bit on these hulls depending on length. For example the 24’ hull I started with had the outside strakes go all the way to the transom. Pictures of 26’ hulls show they end before the transom but it’s hard to tell by exactly how much, 2’? And the current hulls are slightly different so I don’t know I can use them as a reference.

 

[kapnD]

I wouldn’t worry about the lift strakes, it’ll be a lot of work for little or no benefit.
If it were a deep vee hull, it might be an issue.

 

[Bigtalljv]

Thanks. There is more of a discussion going on over where about it.

Extended hull, extend strakes? https://www.boatdesign.net/threads/extended-hull-extend-strakes.67995/#post-944858