Fixing the gas tank problem

WeekiTiki · Posted: Mon Nov 09, 2020 8:03 pm Post subject:

Mine is also an '03 but don't think it's quite this bad

Looking forward to seeing your repairs

Keep the pics coming

thataway · Posted: Mon Nov 09, 2020 8:44 pm Post subject:

From Workbenchmagazine.com. Plus the PVC lumber should be glassed in place, which gives another layer of material which holds screws.

clayhubler · Posted: Mon Nov 09, 2020 10:17 pm Post subject:

When you say PVC lumber are you talking about starboard or it's generic equivalent or are you talking about trex?
I'm planning on gluing pieces of starboard down to secure the tanks after the repair. I also want the starboard in front of the tanks to go all the way up to the lower lip of the splash well so they are more secure.
Thanks

ssobol · Posted: Mon Nov 09, 2020 10:30 pm Post subject:

clayhubler · Posted: Fri Nov 13, 2020 7:20 am Post subject:

Okay, I got some time to start cutting.

Started with the transom. I was expecting marine ply but it was balsa, and looks to be only 1 inch thick. I got all the rot out but there was still a little damp in the edges of the cut. But the heater can blow on that pretty easily, so I'm going to let that go for a few days.

There are more pics in the album

The balsa in the holes on the floor was still totally saturated, not going to dry out like that, so I started cutting on it too.

You can see that the wood is still totally soaked, not rotten mostly but will not dry.

I was hoping that this would be enough cutting, but I'm going to take the back half of the cockpit out next time I go work on it because the balsa is not going to dry. Probably from a foot and a half all the way back to the transom. So here is my next question: do I need to worry about support for the hull? Its on bunks on the trailer. If the top skin is gone and the balsa is gone do I need to worry about distortion when I epoxy this back together?

WeekiTiki · Posted: Fri Nov 13, 2020 11:40 am Post subject:

Yikes

thataway · Posted: Fri Nov 13, 2020 1:39 pm Post subject:

You should be OK as long as the trailer bunks extend slightly beyond the transom, and well forward of the area you are removing. Take a straight edge and double check to be sure.

The wider the bunk boards the better. If there appeared to be any distortion before putting new core in, then I would jack up the boat by the transom, and slide 3/4" cheap plywood under each side up to a bit further tan where the cut outs started.

Another issue, is will there be distortion when you are kneeling in the cockpit. You may want to put some 2 x a 8 boards on top to kneel on. which go edge to edge and contact the area on the inside of the hull over the trailer bunks.

clayhubler · Posted: Fri Nov 13, 2020 1:42 pm Post subject:

That sound like an excellent suggestion, will do

clayhubler · Posted: Sun Nov 22, 2020 5:30 pm Post subject:

Okay, back at it. I've got to say that I am pretty disappointed with the construction methods used by the factory at this point...

As I've been working on this I've been considering how to put it back together. Specifically how to laminate the balsa with the glass and how to make sure I have no voids. I don't imagine it is easy to fill all the kerfs in the balsa with epoxy, and along the edges where the balsa meets the side of the hull. I now can see that the factory did not bother with these details.

I have heard that the water doesn't migrate very far because the balsa is end grain, so it doesn't have the ability to wick away from the access point. This is not true:

Large voids in the sides along the edges of the balsa allowing water to flow back and forth:

This side was dry, but the void is there also:

It looks like the boat sat in the water with a list at some point in the past. The port side is way worse than starboard:

You can see that I've cut a huge area out, but it's obvious that the wet and rotten wood extends much farther forward still. I'm worried that with the kerfs in the balsa wide open and the voids on the side that the coring may be wet all the way to the forward bulkhead.

Please correct me if I'm wrong but there is no balsa under the v-berth? Only pour foam?

Also, is the balsa in the transom sealed from the balsa in the hull? I'm a little worried that the lower part of the transom is going to be rotten as well, especially on the port side. I'm hoping they are isolated. The part on the transom that was rotten looks to me like it got that way because of poorly sealed engine mounting bolts.

clayhubler · Posted: Sun Nov 22, 2020 5:34 pm Post subject:

Here is where I am at now:

I wonder is there an alternative core I could use for the repair? I'm not really a fan of this balsa right now. I have dug saturated pour foam out of boats before though too, and it was supposedly 'closed cell'

thataway · Posted: Sun Nov 22, 2020 6:33 pm Post subject:

I believe you are doing well--and probably would do this repair before moving forward. This will allow stability of the hull bottom.

You are correct that once delimitation begins, the water flows along the surface, or in cuts (kerfs) and can move into a much more extensive area. There aren't really "totally closed cell foams...

Balsa has a number of properties which are in its favor, and that is why it is still being used today. It has good shear and compression strength. The foams and the hex cell materials lack a little in these departments. They certainly can be up used Once the balsa is done right, and not penetrated it is a great material. I was involved with boats built with balsa core (plank) which are now over 50 years old, and the core is still fine, despite several circumnavigations, groundings etc. The secret is that no core penetrations, without the proper sealing.

The only C Dory I can speak to about the transom and bottom was my 2003 25' C Dory I document in the photos and repair, that they were sealed off. They should be because of the way the boat is built. You don't want balsa to balsa at at hard and structural edge....

Yes, boats are all built to some price point..and weight point etc. One of the around the World racers (actually several) leaders, is involved with do a major hull delimitation repair on a a multi million dollar 60' boat...under sail, alone. Sort of like rebuilding your space craft as you get ready to land on the moon....

Thank y ou for documenting the great work you are doing!

C-Wolfe · Posted: Sun Nov 22, 2020 10:18 pm Post subject:

To answer your question about wood core under v-berth, go look into my photo album. I had to open up my v-berth because of a water/gas leek problem and decided to remove all the foam for extra storage. In a couple picture you can kind of see under my tools that the wood core stop about 4-6 inches past the bulkhead. let me know if you need more accurate measurement, but I don’t think you will need to go that far.

thataway · Posted: Mon Nov 23, 2020 12:23 pm Post subject:

I just posted a thread about cores, Balsa vs Foam, proper technique etc with links to West Systems 396 page PDF book onus of epoxy. (not an endorsement for West Systems, although that is what I use currently).

I posted a new thread rather than on this particular thread, because it has relevance to all balsa core repair.