1969 Larson - Big Project

[avpaulb]

Re: 1969 Larson - Big Project

Looks like foam core ( little squares of foam 3/4"ish thick ) instead of balsa core on your hull sides.

For some reason I think that is probably Structural and should be replaced.

More pics and info needed though.

YD.[/QUOTE]

The only pics I have of it are those I've posted. HOWEVER, there is a guy doing a repair right now on the forum that has the EXACT same situation going on:

http://forums.iboats.com/showthread.php?t=544365&page=4

If you look at posts #56 and #78 he has a couple of good shots that show precisely what I had going on. The foam ran all the way up the hull sides, under the cap, from bow to stern. On top of the hull there was carpet glued in.

He isn't planning on doing a deck repair. When I removed my deck and started grinding up the sides of the hull to have a place to lay glass, that foam stuff just started coming right off. So, I removed it.

I figure I have two options...

A) Figure out a way to replace the foam. It wasn't squares, as you described, it was definitely blown in or somehow poured in.

B) If it was structural, could I not skip the foam idea and lay up some glass applications instead?

I'm good with either option. I think I've devised a way to do the foam in my head. It would be a ROYAL PITA, but I'm pretty sure my idea is solid.

I need to continue with the transom, stringers, deck anyway before I get to that point, so I have time to debate ideas!

 

[avpaulb]

Re: 1969 Larson - Big Project

Drawback of moving boat outside for the project... Montana weather can really screw you up! It's been in the 40's everyday!

Oh, well. Back into the 70's and 80's again, so back to work tonight!

 

[Yacht Dr.]

Re: 1969 Larson - Big Project

If it was poured or blown .. or even sheeted its still the same..

I think its structural.

Your outer skin is probably thin and your inner skin is probably thin..

To add more glass is gonna cost you more then adding back the core I think.

YD.

 

[avpaulb]

Re: 1969 Larson - Big Project

If it was poured or blown .. or even sheeted its still the same..

I think its structural.

Your outer skin is probably thin and your inner skin is probably thin..

To add more glass is gonna cost you more then adding back the core I think.

YD.

I guess that would depend on what I would need to core it with. I have an idea in my head on how to do it with the 2lb marine foam. I'll work on drawing up a picture and see what you think. The foam layer itself wasn't very thick, maybe 1" at the absolute thickest point. And it tapered to the top just below the cap. I figured the total volume of foam needed to do it would be about 5 sq. ft. Then it was coated with a single glass layer and glue. The trick is to build the layer of glass FIRST, then pour in the foam.

I did a rough calculation on the area that would need to be covered if I just glassed it. It would take about 6-7 SQUARE YDS of glass per application to wrap around. I was thinking probably 2 layers CSM with 1 or 2 1708.

 

[avpaulb]

Re: 1969 Larson - Big Project

Pardon my handwriting on this... I type EVERYTHING! But here is the general idea:

1.

2.

3.

Maximum foam depth is about 1", at about 20" high, at roughly 36-40' around the deck. This gives me 5-6 cubic feet of foam. According to USComposites, that would be about 2/3 of their 16 pound kit. And, an additional 300-360 lbs of float.

I'm also working on a conceptual tool for injecting the foam.

Or, I can glass it.

 

[avpaulb]

Re: 1969 Larson - Big Project

Quick question...

I got the transom all tabbed in last night. Noticed a bubble formed overnight. How should I handle that? Grind out and patch?

 

[jbcurt00]

Re: 1969 Larson - Big Project

Yep,1 of the big advantages glass boats have over tin: When they are damaged or the repairs don't go exactly 'right', ya grind 'em down & give it another go

 

[avpaulb]

Re: 1969 Larson - Big Project

Yep,1 of the big advantages glass boats have over tin: When they are damaged or the repairs don't go exactly 'right', ya grind 'em down & give it another go

It was so perfect last night too! Woke up this morning... bubble. Darn. Oh, well. Easy fix.

 

[Yacht Dr.]

Re: 1969 Larson - Big Project

I think you should be ok with your pour foam plan.

JB is right on..just grind a patch .. no biggie ..

YD.

PS. I like your thinking outside of the box attitude .

 

[avpaulb]

Re: 1969 Larson - Big Project

I think you should be ok with your pour foam plan.

JB is right on..just grind a patch .. no biggie ..

YD.

PS. I like your thinking outside of the box attitude .

I use the cloth method working with fiberglass on other projects. Works great. The key is to use something that can really soak up the resin. I'll document it if I pull it off. Later.

 

[avpaulb]

Re: 1969 Larson - Big Project

In the meantime... another late night update. My last two day's progress.



A useful new tool. (The fluid pump for 5-gallon drums).

Transom fillet. My "tribute" got a bit pooched by the acetone. You get the jist.



Tabbed in...



And two additional 1708's. I can hang off this thing right now. And I'm a relatively big dude...



And she got her first complete acetone bath in preparation for stringer work!

j

I did have a couple of air pockets that formed in the tabbing last night. I chose to sand out, fill with PB, then re-tab with two 1708 patches. You can't even tell they were there now.

All told the trans is rock solid.

Unfortunately my manly duties require me to go camping with the family all weekend. No work to follow until AT LEAST Sunday. Oh, well. I better catch at least one fish this summer! Fishing a lake I have actually not ever been to (a rare occurrence). Maybe I'll post pics of that mayhem for a change!

 

[Woodonglass]

Re: 1969 Larson - Big Project

I'd say the transom turned out really well. Hopefully it'll be 30 years before anyone ever sees the iBoats tribute!!!!!

 

[Yacht Dr.]

Re: 1969 Larson - Big Project

Thats great man !!

Go slay some fish now and take a break .

YD.

 

[avpaulb]

Re: 1969 Larson - Big Project

Unfortunately the fishing was POOR. But a good break.

I got to sit lakeside for two days wishing I had a boat! Ha!

Back on it tomorrow!

 

[avpaulb]

Re: 1969 Larson - Big Project

Well, it looks like I'm going to have another short week to work on the project. Extra long fishing trip over the weekend.

So my plan for the short week is to at least try to have my stringers measured, cut, and tabbed in.

There seems to be an ongoing debate on what to glue the stringers in with: PB or PL...

I like the idea of PB because it will set really quick. This would be handy if I'm able to lay out and cut the stringers pretty quick.

Anyway, any thoughts?

 

[Woodonglass]

Re: 1969 Larson - Big Project

PB for the exact reason, SPEED. I used to use the PL but NO MORE.

 

[avpaulb]

Re: 1969 Larson - Big Project

Yeah, that's what I thought.

First things first... trying to recreate my deck height. Challenging.

 

[Woodonglass]

Re: 1969 Larson - Big Project

Did you mark it on the sides of the hull when you removed the old one?

 

[avpaulb]

Re: 1969 Larson - Big Project

Did you mark it on the sides of the hull when you removed the old one?

As best as possible. I also have some back-up pictures to help as well.

 

[avpaulb]

Re: 1969 Larson - Big Project

Got a bit of work done on manufacturing stringers tonigt. First step, had to construct something effective to level my main stringer and something to scribe with.



Handy little tool. Worked well. I've decided to do some lateral bulkheads between all of the stringers, starting with a full width bulkhead to cap the bilge.



Using this method will be helpful since my stringers can't run full length, as well as with attaching the decking later. As you can see, an 8 ft sheet of ply doesn't quite reach full length!



Ultimately it will look something like this:



But with any bit of luck, tomorrow I hope to be able to cut the remaining stringers, sand and adjust as needed, get some resin on them, level and glass in! We'll see!