Materials For Bedding New Stringers In

[mspring]

I was just watching a video from ship shape t.v. and they said the wood stringers should not contact the hull directly because of the "hard joint" factor. I had not thought of this on the stringers, I had read post on this same subject pertaining to deck and hull joints.

What options do we have? I was originally going to use resin. Now I wonder if that would create a hard joint.

 

[rockyrude]

Re: Materials For Bedding New Stringers In

I've been following this forum for quite some time, and the "standard" method of bedding stringers has been peanut butter. This is the method I used, recently I noticed our gurus are saying that heavy duty construction adhesive (PL1000) is acceptable. You definitely get more working time with the adhesive.

 

[Robj]

Re: Materials For Bedding New Stringers In

Just do a search there are many posts on this topic. I would still use the peanut butter method as opposed to PL premium or some other polyurethane adhesive.

Have a great day,

Rob.

 

[Capt. Mike]

Re: Materials For Bedding New Stringers In

I have not been here long what is this about peanut butter???
new one me. I'm from Tennessee so can you learn me the peanut butter thing.lol

 

[Coors]

Re: Materials For Bedding New Stringers In

Peanut butter is resin with fillers mixed in to it.
I just replaced my stringers and engine mounts, using MAS epoxy,;had 5 hours of working time with medium hardener, which made things so much easier.

 

[BillP]

Re: Materials For Bedding New Stringers In

This isn't a do or don't do situation. You have to put what SSTV said in perspective (which is something SS never does). Since the beginning of time boat mfgs have set stringers directly on the hull and had zero problems...most still do and bottoms aren't cracking. In recent yrs SOME of the boat mfgs place stringers off the hull. There are reason why... mostly because they are using thin hull laminations, cores of various materials (that cannot handle single point compressing) with thin, thin stringers. An example is a Pursuit 24' center console that used a thin (but strong) biaxial hull skin with 1/2" ply stringers & bulkheads...yes 1/2" ply. They set the ply on foam (looks like swimming pool "noodle" material) spacers to keep the ply from hitting the hull during flex.

Do you need to stand your stringers off? Probably not if you consider the millions of old boats that didn't and add the number of mfgs that still don't...and compare them with the few that cracked (if you can find one).

 

[mspring]

Re: Materials For Bedding New Stringers In

Yeah BillP, If I did everything sstv recommends I will have spent enough to buy 2 or 3 20 footers like mine lol!!!

Originally my stringers were not bedded down with anything. Only the one layer of roven. And no glass was on the stringers where the 2x4 cross members that support the deck ran across.

So are you saying I shouldnt be concerned with a hard joint?

 

[oops!]

Re: Materials For Bedding New Stringers In

billp......

good post,,


i was also told to use sikka flex to bed the stringers....

however.....the people that have done this a thousand times,,

have suggested the "peanut butter" mentioned earlier...
another is called micro ballons....sitll a resin mix

my choice is what the standard is on this site

 

[BillP]

Re: Materials For Bedding New Stringers In

It doesn't matter what is used to set the stringers. All it does is hold them down for glassing. I use thickened resin...because it's easy and available.

Just for giggles I may try another method someday. Technically speaking, epoxy has enough strength and tenacity to hold stringers down without using glass to hold them. Wouldn't it be nice just to glue down pt wood stringers and forget about glassing? They could be epoxy coated to keep water out for water absorbtion (weight) issues.

 

[Robj]

Re: Materials For Bedding New Stringers In

The problem with using a polyurethane adhesive to bed stringers with is that you will get the stuff everywhere when you are working. Some also take days to set, but there are some quick ones available. I do not think resin will stick to a stringer that is covered with polyurethane adhesive. That is why I think it is better to go the peanut butter method. Bellow is a link that also discussed this topic a while back.


http://forums.iboats.com/showthread.php?t=225893&highlight=Hard+spots

Have a great day,

Rob.

 

[drewpster]

Re: Materials For Bedding New Stringers In

I am starting the process of replacing the main timbers (stringers) that run full length fore and aft in my boat's hull. I am replacing the cores because they are wet. The best advice I have gotten so far on the subject is to "do them the way they were originally done". "They were originally set directly to the hull and they lasted 39 years". So it is my guess that if I repeat the original process the stringers should last at least as long as I own the boat and maybe many, many years after that.
Kinda takes the mystery out of doing the job doesn't it?

 

[Robj]

Re: Materials For Bedding New Stringers In

I am starting the process of replacing the main timbers (stringers) that run full length fore and aft in my boat's hull. I am replacing the cores because they are wet. The best advice I have gotten so far on the subject is to "do them the way they were originally done". "They were originally set directly to the hull and they lasted 39 years". So it is my guess that if I repeat the original process the stringers should last at least as long as I own the boat and maybe many, many years after that.
Kinda takes the mystery out of doing the job doesn't it?

I would use that as a guide for my repair and then go from there. Lots of things have changed since the boat was originally built, both materials and manufacturing processes. When you say the original stringers were set on the hull, that is OK, just make sure you bed them in peanut butter to avoid any hard spots.

Have a great day,

Rob.

 

[BillP]

Re: Materials For Bedding New Stringers In

In my opinion there's a lot of un-necessary concern going around about attaching stringers. I didn't mentioned it previously but most boat mfgs just set the wood down and glass it...some use raw resin to tack them but typically there's no bedding, no extra glass, no nothing. They depend on the glass to capture the stringers (reflect on the Pursuit post where their stringers have soft foam spacers under them). It's the same deal with transoms...resin (sometimes thickened) between ply and hull and no glass, no nothing between the ply layers. These are proven methods backed by 50+ yrs of successful fiberglass boat mfg. They still do wood stringers and transoms with the same methods as were done in the 1950/60s. There's no advantage in re-inventing what the pros have already proven successful...unless it just makes a person feel warm and fuzzy.

bp

Afterthough edit on "hard spots". Boat factories pretty much cut and fit better than us home project guys...so we use "peanut" whatever to make up the difference for a good bearing surface. How good your fit is makes the big difference between using something under the stringer or not.