New floor/sole tabbing to hull or skin?

[Trihulled]

Hello hello! I'm relatively new to the forums so if I am missing anything obvious please feel free call me out or point me in the right direction.

I'm restoring a 1972 Thunderbird with the cathedral tri-hull.

Strings have all been replaced and glassed in and I'm just about ready to put in new floor.

Now the question. There is the hull and then there is a inner fiberglass skin that is not mated to the hull. When I cut out the floor it was only glassed to this skin and now the skin layer is "floppy" without the flooring. I've seen a lot of different stuff on the inter webs. My question is when bedding down the new floor would it be better to bed into the hull or just tab the skin?

(Pic soon)

My plan (absent of any insight gained here) is to run the floor all the way to the hull and bed it with thickened resin and then run over it with regular resin. After that, since the skin lays flat on the hull at the bottom, to tab the skin into the floor. Basically this means not tabbing the hull to the sole. Let me know what you guys think.

 

[Woodonglass]

Pics are gunna be necessary cuz you for sure have me confused

 

[Yacht Dr.]

Pics are gunna be necessary cuz you for sure have me confused

I think he means his deck liner goes down the sides of his hull..but not tied to it..only tied to the floor.

I remember another cat, some years ago, doing the same thing. I dont know if bedding it down @ the hull is gonna hold without glass. You could try it..worse that could happen is it would pop. But you have it glassed to the liner and screwed and glued to the stringers..so its not going anywhere. I probably wouldn't bed it down..just glass it to the liner.

Is there a little lip that the deck rests where it meets the hull?

 

[Mark72233]

Trihulled, welcome to iBoats and yes lots of pics. I love the old Thunderbird trihulls. The first boat that I can remember my dad having was a 16' Thunderbird tri with a Mercury outboard, I think it was a 65hp. I am presently restoring his old 1972 Thunderbird Formula 233, its been a blast. Good luck with your boat and I will be tagging along if that's ok.

 

[Trihulled]

No Title

Here are some pics guys and thanks for all the reply's.




Yacht Dr. no, there is nothing where the deck meets the hull and no indication there was any sort of connection at any point.

​Mark72/233 yeah it's a pretty neat 23 footer. Please do tag along, I'll be creating a thread shortly with the start-to-present details of the restoration.


Another idea I just considered is this: I would 'like' some peace of mind on waterproofing by having a seal between the floor and hull. Tabbing it properly would be a nightmare and would mess with the thickness where the liner sits. I might do what I mentioned, fill the edge with thickened resin, and then do one easy 5-6in strip of some thin glass behind the liner, just to seal it up.even if the edge pops it would keep the seal hopefully. just a thought.

 

[Yacht Dr.]

You could do that..or just seal up the edges of the ply..glass over the top..then tab to the liner. If water ever got through the hull/deck joint, the wood in there should be ok to shake it off.

I just dont know why they didnt tab the deck to the hull in the first place. Could there be a reason for that? hmm..I dunno.

 

[Trihulled]

I've decided to do a thick bead of PL around the edge, the ply edges are already sealed. Then I will use cabosil/thickened resin to fill and fillet the joint and tab in the liner.

 

[Yacht Dr.]

Sounds like a plan. Keep us updated with pics

 

[Woodonglass]

Be advised that Polyester resin may have issue with adhering to the PL adhesive. At the very least you need to let the PL cure for a minimum of 3 days prior to laying any resin on top of it AND you need to abrade it afterwards and wash it down well with acetone.

 

[Yacht Dr.]

Be advised that Polyester resin may have issue with adhering to the PL adhesive.

Im thinking that he is using the PL for a 'gasket' between his deck and hull. Kinda like an expansion joint. Then the PB is for his liner to deck glass..basically its gonna be a form so he can layup. Not even sure if his PB will touch his PL in the LD after his QC

 

[Woodonglass]

I've decided to do a thick bead of PL around the edge, the ply edges are already sealed. Then I will use cabosil/thickened resin to fill and fillet the joint and tab in the liner.

Hmmm, I dunno, it sounds to me like he's planning on filling the gap between the deck and the liner with PL but I AM just an Old Dumb OKIE and I've Been Wrong MANY times before!!!!:doh:

 

[Trihulled]

Im thinking that he is using the PL for a 'gasket' between his deck and hull. Kinda like an expansion joint. Then the PB is for his liner to deck glass..basically its gonna be a form so he can layup. Not even sure if his PB will touch his PL in the LD after his QC

Correct, this is the plan. PL is just to seal the deck/hull joint and give it some support and flex. The PB will likely touch the PL but I'm not too concerned about it bonding or not.

 

[Yacht Dr.]

Just make sure you have some way for water to run into the bilge. You dont want a sealed channel in there. Ya know..just in case a few hull/deck screws start leaking at the rub-rail..

 

[Trihulled]

What weight and type glass would you guys suggest for the tabbing and the floor laminate? Woodonglass I have been watching FriscoBoater's Sea Ray videos on youtube (he mentions you) and he uses 1 layer of 1708 for the tabbing. Since mine doesn't seem as "structural" I don't know if I need to go that hefty? The floor layer I was thinking 2 layers of mat but not sure the weight?

 

[Woodonglass]

I'd still recommend that you use the 1708 for the tabbing and 2 layers of 1.5 oz CSM for the floor would be my recommendation. This might be of interest...Fabricating Decks, Stringers, and Transoms

 

[Trihulled]

Thanks, do you recommend grinding down to the bare glass on the liner up to the 9 inches of overlay? I don't know how well the new layers would bond if i leave it as paint or primer, but that's a decent amount of work so I want to be sure.

Also, after the last layer is in, should the edge of the CSM be fine sanded to blend? recommended grit? Thanks in advanced.

 

[Woodonglass]

Yup you gotta grind it or it won't stick unless you do. I'd feather the CSM using 80 grit.

 

[Trihulled]

No Title

Update: Got all my glass in Thursday night so I went out yesterday to do the tabbing. The vertical supports in the liner are a real pain haha but it's coming out nicely.



What's the best way to get a nice flat surface with the gel coat? I'm not too keen on sanding the whole floor but I want it to be decently smooth, at least on the vertical sides. I haven't really thought about how to finish/texture the walking surface. Maybe that non-slip texture that boats have pressed(?) into the paint, maybe go big and do teak anyways, ideas and suggestions are always welcome.

 

[Trihulled]

Also, started a log on the entire restoration here: http://forums.iboats.com/forum/boat...09-1972-thunderbird-cathedral-restoration-log