How strong is she?

[ashedd]

I thought this topic might get more traffic in this forum..

I have a 20' Tollycraft cabin cruiser with outboard, it's 3/8" ply hull with a layer of glass from the factory. I had a section of the garboard peel off several months ago that had to be repaired. The boat was new to me and I was checking her out in rough(ish) water, and after a couple days of this I noticed the bilge filling up and eventually I hauled it out to find the garboard piece missing. My boatyard neighbor showed me how that section of hull had a bad repair done to it at some point and that it likely flexed enough over time to let go. Anyway, this got me to thinking about how strong is a 20' plywood boat?

I'm a little spooked about rough water now, even though my repair is very strong, and I'm wondering just how strong the boat is. It has very large beefy stringers but I'm concerned about hitting something submerged. Outside of this repair, I found some cracked, or cracking, frames that I sistered(likely from the trailer it stayed on), and rot in the starboard transom corner. With the transom I drilled a ton of holes and filled it up with penetrating epoxy, it's as solid as concrete when tapped. The "keel" on this boat looks like it just serves as a place to screw the garboard planks and outer keel. It appears to provide little strength, it gets this from the large stringers, that's how it looks anyway.

Submerged logs are my concern once I go into saltwater, it will be my first time in the salt.

 

[ondarvr]

If the hull is still in good shape it should be fine, strength wasn't the issue with plywood hulls. Wood flexes, this helps it absorb impacts and gives a softer ride.

The rot in the transom could be an issue, penetrating epoxy doesn't really live up to its hype, it will make it a little better than it was, but doesn't restore it or stop the rot process.

 

[Woodonglass]

Remember what they said about the Lusitania!!! No matter WHAT the hull is made from there are always circumstances that No Boat Hull can stand up to. In rough water there's always a risk, but your wooden hull is no more at risk than a full fiberglass hull. If a wave picks your boat up and slams down hard onto a submerged sharp object... Well you get the gist of it.

 

[Ned L]

Just like 'glass hulls, there are all sorts of "robustness" of plywood hulls. Everything from basically bullet proof tanks to lightly built hulls that need some care. I'll say that a 3/8" bottom on a 20ft boat seems a bit on the light side. How far apart are the frames spaced? ....... The fact that some have cracked is a bit concerning. it sounds like she is built on the light side.
Drilling holes in deteriorating wood and filling with epoxy is really pretty much for cosmetics and won't return any structural strength. Be sure you don't have any resulting structural concerns here.

 

[ashedd]

Just like 'glass hulls, there are all sorts of "robustness" of plywood hulls. Everything from basically bullet proof tanks to lightly built hulls that need some care. I'll say that a 3/8" bottom on a 20ft boat seems a bit on the light side. How far apart are the frames spaced? ....... The fact that some have cracked is a bit concerning. it sounds like she is built on the light side.
Drilling holes in deteriorating wood and filling with epoxy is really pretty much for cosmetics and won't return any structural strength. Be sure you don't have any resulting structural concerns here.

Tollycraft is supposed to be known for making vessels that are seaworthy for the PNW waters, but I'd like to see 1/2" ply and not 3/8. I think there are 5 frames between the transom and bow, which is an improvement over the two frames that my 16' plywood boat has. Where the frames were cracked is exactly where the boat sits on the trailer, so hopefully that's what did it. This boat lived many years on the Columbia river from what I've found. A leaky caulk job appears to have let water come in from the gunwhale and caused damage over what looks like years, I have that area stabilized for now. The transom rot looks to be from a transducer that wasn't sealed well or at all. I don't understand how people can drill into their hull and not seal it up properly. This winter I'll replace those frames and look at the transom closer. I want to get the transom up to par to accept an e-tec and I may build it up so I can use a 25" shaft motor. The boat has tons of freeboard but the transom is a little low, still well about the water though, the splash well is really large too. I keep the boat moored and it won't be on the trailer unless it has to be, I may even sell lthe trailer since it's junk.

 

[ondarvr]

When I was young we had several wood boats in the size range, and some a little bigger, I don't think any had 1/2 plywood. Tollycraft made quality boats, and if it was under built it wouldn't have survived this long.

 

[Ned L]

Very pretty! .. I am familiar with the Tollycraft name ( mostly through their early '70's glass boats). They do build a nice boat, and it certainly looks like yours is nicely taken care of.

 

[ashedd]

I wish the splash well didn't eat up 2 feet of space... removing the well would necessitate converting to an inboard or I/O me thinks, hardly worth the trouble.

 

[Woodonglass]

IF you ever encounter a big backwash...You'll be wanting the splashwell to be even bigger. It can/will save your boat!!!!

 

[mickyryan]

id like my next boat to be something like that but with a hard top and I'm about done with fiberglass lol omg I'm still itching!

 

[ashedd]

id like my next boat to be something like that but with a hard top and I'm about done with fiberglass lol omg I'm still itching!

I want to do a hard top by was told it would make me too top heavy

 

[mickyryan]

not if you use light weight materials and don't listen to what everyone says , people tend to make blanket statements without having any idea what they are talking about, if you build the top heavy , it might be a problem however I'm betting you could build it under 100 lbs and you would be just fine.

 

[ashedd]

I figured I could use really lightweight materials, maybe balsa cored composites. If I still worked in my old field I could have snuck home some honey comb. Biggest problem is me, I'm 6'7" and would love to be able to stand up. I can always take the floor out lol

 

[Woodonglass]

I agree, Light weight fabrication would be pretty simple to do. Luan plywood with glass would probably come in Less than 50lbs.

 

[mickyryan]

do like I did I used 2 sheets of tri ply underlayment and sandwiched foam in between then I wrapped top in fiberglass matt just for waterproofing then covered with white elastomeric paint for further waterproofing I was able to lift the top up a ladder and onto boat by myself so it cant weigh too much and it had sides on it as well .