bedding strings and stuff!!!

[Axkiker]

So I have been watching the guy on Youtube who completely redid a SeaRay. I noticed he bedded his stringers in with PL Glue. Is this an accepted method.

Reason I ask is I am replacing the front section in my open bow boat that the seat cushions are built on. I had thought about using pl glue as well but was told not to bed things with glue, i should use PB.

Any thoughts on using PL glue for bedding items to a hull

Thanks

 

[Woodonglass]

Re: bedding strings and stuff!!!

You can, and lot's of guys have. The problem with PL is it takes a minimum of 72 hrs for the stuff to cure and stop "outgassing". If you attempt to glass over it before this stops the resin and glass with have MAJOR adherance issues!!! If you get messy with it and spread it all over the hull then you'll need to grind it off before glassing. If can get Air bubbles and Voids in thick layups too! I used to recommend it but for the previously mentioned reasons I now recommend using PB. But...It's your boat and you're free to do as you see fit. Both WILL work.

 

[ondarvr]

Re: bedding strings and stuff!!!

It doesn't really make much of a difference what you use, if anything at all, the idea is to just not let the plywood rest against the hull. There are many options, something like PL, PB, foam strips, small foam spacers every foot or so, a jig to hold it up with no contact, wood shims that are removed, etc.

Or you could do it like the vast majority of small boat builders do and use nothing, just lay the plywood stringers in place on the hull and glass over them. This really isn't the correct way, but they get away with it 99% of the time.

 

[Axkiker]

Re: bedding strings and stuff!!!

You can, and lot's of guys have. The problem with PL is it takes a minimum of 72 hrs for the stuff to cure and stop "outgassing". If you attempt to glass over it before this stops the resin and glass with have MAJOR adherance issues!!! If you get messy with it and spread it all over the hull then you'll need to grind it off before glassing. If can get Air bubbles and Voids in thick layups too! I used to recommend it but for the previously mentioned reasons I now recommend using PB. But...It's your boat and you're free to do as you see fit. Both WILL work.

Good info.

Does PB have any issues with being too ridged as a bedding? After considering what you mentioned above im also leaning toward PB but am curious.

Thanks

 

[Axkiker]

Re: bedding strings and stuff!!!

It doesn't really make much of a difference what you use, if anything at all, the idea is to just not let the plywood rest against the hull. There are many options, something like PL, PB, foam strips, small foam spacers every foot or so, a jig to hold it up with no contact, wood shims that are removed, etc.

Or you could do it like the vast majority of small boat builders do and use nothing, just lay the plywood stringers in place on the hull and glass over them. This really isn't the correct way, but they get away with it 99% of the time.

Interesting info!!! I guess that the strength isnt really coming from the bedding but the tabbing. This is all new for me so just learning as I go

 

[Woodonglass]

Re: bedding strings and stuff!!!

None. Actually More Flexible than if the wood stringer were laying flat on the hull.

 

[Decker83]

Re: bedding strings and stuff!!!

My stringers were placed on top of some csm that was wet out and rolled up into a 1/4" round tube..

The strength comes from the fiber glass and not the wood.. You could use a cardboard tube and lay the right amount of glass and use that for a stringer.. But I would not recommend it..

 

[Woodonglass]

Re: bedding strings and stuff!!!

The strength comes from the fiber glass and not the wood.. You could use a cardboard tube and lay the right amount of glass and use that for a stringer.. But I would not recommend it..

This ^^ is True. Since this topic has been brought up, I've been toying with this idea, and my next boat, (if there is one) I will install the stringers like this.

Blue foam to keep the wood off the hull. Bracing to hold them in place while the filleting and tabbing cures. I'm betting it'll work just fine!!!! I'm either gunna do that or make 4" wide foam stringers oughta the same blue foam and cover it with 240z woven roving and two layers of 1808 biax. I gotta figure the costs of those first!!!:faint2:

 

[GT1000000]

Re: bedding strings and stuff!!!

The strength comes from the fiber glass and not the wood.. You could use a cardboard tube and lay the right amount of glass and use that for a stringer.. But I would not recommend it..

Partially true...and you even said it yourself..."You could use a cardboard tube and lay the right amount of glass..."

Part of the strength does indeed come from the fiberglass, but also from the wood when it is used as part of the construction...

Explanation: The following is my interpretation, condensed from several write ups I have read regarding this issue...

If wood is used as a sub structure in a fiberglass boat, it is not only a form for the fiberglass but also shares in the work load, since adding sufficient fiberglass to carry the entire work load would in essence negate the need for a wooden sub structure as evidenced by fiberglass boat construction which use a urethane foam type sub structure, which in and of itself would not be capable of supporting the work load of the hull's structure, therefore the fiberglass cloth that is used in the construction of these foam substructure type boats is engineered to carry the entire work load, generally speaking this type of construction requires several more layers and different thickness/weights of fiberglass cloths to properly and safely carry the work load...

One of the major reasons boat manufacturers have used plywood in the construction of consumer boats is the relative cost savings over building a boat out of much more expensive specialty foams, molds and greater amounts of fiberglass resin and cloth...

The other side of the coin are "exotic" materials such as Kevlar and Carbon Fiber among others which require even more specialized building techniques, weigh less, cost more and make for extremely strong and fast hulls...

Some of the latest consumer boat building techniques using these "exotic" materials are becoming more popular, as prices go up along with buyer expectations and as time goes on, they may begin to imitate the consumer electronics market, which at first, a new gadget cost an astronomical amount of money, but as soon the the technology becomes common and advances, the cost go down exponentially...

Happy Humpday!