Questions on Fiberglassing New Stringers in

[rozicrc]

Hi Folks,

I purchased a project boat planning on having a motor rebuild be the extent of the work. Of course, the 180 HP rebuild was ready to go in and I decided to check the transom "just in case." 8 weeks later, I've got the transom out, a false skin built for the new transom (I am going with Seacast polyester resin to keep this from ever happening again). I've got everything out of the boat, deck torn up, and stringers exposed. There was a manufacturing defect that would never allow water to drain out of the port side - no drain holes on that end.

As one would expect, the stringers and crossmembers on that side are pretty soft for the stern quarter and one spot in the fuel tank bay. I was very surprised to see the method of manufacture - only 3/4" treated covered with resin, and glass only in spots for about 6 foot lengths. I was also very surprised to see that most of the sections were not rotten - just where it started in two local spots.

I am planning on buying marine plywood and cutting in sections with a lap joint and glassing in the sections. I have a few questions and would appreciate any help on these questions:

1.) what weight glass can I use (1708 woven roving is what I am planning on) for glassing in the new joints?
2.) Should I bother redoing the good stringer spots just to be sure they stay healthy, or is just resining in wood in spots an accepted method of construction?
3.) There is a massive debate on the site on whether to butt up the ply stringers to the hull - I am planning on putting 1/4" foam under and building up glass around for structural - any boat builder who can help settle this arguement once and for all?
4.) Deck glass - would like to go over 5/8" marine and glass in, what weight glass should I use? Is there any downside to using 1708 for this?
5.) I am considering just spraying gelcoat versus laying down carpet, has anyone done this successfully and if so how did it last?

Thanks in advance for your help!

Ron

 

[oops!]

Re: Questions on Fiberglassing New Stringers in

hi ron.


ok....some issues here.

first of all......the current pressure treated wood is wet....it will take forever to dry it sufficently for it to take resin. i would remove them and replace them.

i am a big fan of pt ply for the stringers and transom. if water does get past the new glass, they will only get wet. not rot.

your use of marine plywood will not gain you anything at all in this usage.
exterior grade plywood will be fine.....what ever wood you choose.....you need to start drying it now.....

ext grade ply will need a week with a fan on it.
pressure treated wood will need about a month with a fan to get dry enough to absorbe the resin.

resin coating the wood will work.....but. it is allways better to add a layer of glass. resin by itself is very brittle and will tend to crack and peel like old paint...if you add a thin layer of glass (.75 oz) it will be permamant.

1708 BI AXE will be correct for the stringers.
place the chopped strand mat side AGAINST THE WOOD AND THE FIBERGLASS.
also make sure that the grain of the fabric is going legnth ways not up and down....(just trust me on this)

when you put the new stringers in the boat....use small shims to keep the wood from touching the hull.....(if the wood touches the hull it is called a hard joint....not good)
under the shims and in the gap....use peanut butter, pl9000 construction or even kitty hair as a bedding compound. (if you choose the pl9000, it must be fully cured before you glass over it)

as far as using 1708 as a top glass covering. that is really overkill and will leave ridges.
you need a minimum of 8 oz for your deck....(use the 1708 if you wish on the tabbing in of the edges)
what i uasually use for deck coverage is 2 layers of 1.5 oz matt, and a 6oz finishing veil (this is a very thin woven roving product....you can see it at wall mart).
this will give you a smooth surface to gellcoat to.
the three layers of glass can be laid all at one time.

as far as using gellcoat on the deck.....yes....i highly reccomend it.
it will be slippery....but that can be overcome by adding some non slip.
actually i just carpet over the gellcoat. in doing this....the deck is good for 40 years.
you dont have to spray the gellcoat on the deck....it can be painted on. but if you know a good gellcoat spray person....then why not?
(you cant shoot the gellcoat over 40 thou or it will crack...the tagret thickness is 35 thou)

i hope i covered every thing......if not....just yell.

cheers
oops

 

[oops!]

Re: Questions on Fiberglassing New Stringers in

by the way.....welcome to i boats.
take pictures of your project and start a thread here. you will get lots of help.

cheers
oops

 

[rozicrc]

Re: Questions on Fiberglassing New Stringers in

you, my friend, are a rockstar - thanks for the help!

 

[drewpster]

Re: Questions on Fiberglassing New Stringers in

oops rock star? lol

 

[oops!]

Re: Questions on Fiberglassing New Stringers in

oops rock star? lol

once upon a time i had the hair for it...just couldnt sing worth a damm....lol

 

[rozicrc]

Re: Questions on Fiberglassing New Stringers in

picked up the lumber today and drying, so we are moving in the right direction. Insofar as the gap, what is typical tolerance between the stringer and hull - 1/8 to 1/4"? Where can I pick up the filler most reasonably? I'm not familiar with any of the products you'd noted, If there is one I can use a caulk gun to apply I would go with that if possible.

Thanks again in advance gents

 

[Friscoboater]

Re: Questions on Fiberglassing New Stringers in

Check out my thread. Lots of pictures and videos to help with your resto. Plus you get to see me screw up from time to time.

 

[oops!]

Re: Questions on Fiberglassing New Stringers in

thick as a popcicle stick on the flat.

the pl9000 is a tube type adhesive.

but if you use it....it MUST BE FULLY CURED before you glass over it.....that is about 72 hrs....not the 24 the tube says

 

[oops!]

Re: Questions on Fiberglassing New Stringers in

peanut butter or kitty hair is an exellent choice if you dont have the three days.....it can be glassed over right then and there...
just dry fit the stringers....then lay them over on the side and take a putty knife and smear some stuff in the channel.....then drop the stirnger on the shims in the goo.....then take a smaller round nose putty knife and walk down each edge.....done.

for the recipy for peanut butter...search hull extension in progress....there is an index on the first page....look for oops super dooper peanut butter.

and the above post by frisco boater is also a really good information source

 

[rozicrc]

Re: Questions on Fiberglassing New Stringers in

thank you gentlemen

 

[rozicrc]

Re: Questions on Fiberglassing New Stringers in

poured the seacast today, actually went easier than I thought short a little bit leaking onto the outside of the boat - cleaned up easily with brake cleaner though (as does anything else). Boy does it get hot though, I chilled the seacast to 55F before pouring on an 80F day and it still took off, but fortunately was around 30 minutes working time.

I'll dump photos on the site when I replace the cable (cat chewed the current one up).

 

[rozicrc]

Re: Questions on Fiberglassing New Stringers in

I've got 4 3/4" ply stringers glassed into the hull, I'd like to remove one side at a time (port first then starboard) to make this easy on myself. Do I need to replace them one at a time or can I do two adjacent at a time?

 

[Greg Mrozinski]

Re: Questions on Fiberglassing New Stringers in

You can do two at a time by side as long as you have space to work between them.