Western red cedar for stringers?

[chconger]

Hi All

Any reason not to use it in my '1990 SSV 199 Glastron for stringers?

Seems like rot resistance is on par with Honduran Mahogany.

I would prefer White Oak but can't find it in 12' length here.

Thanks
Chris

 

[Bondo]

Re: Western red cedar for stringers?

Ayuh,.... I usually use 3/4" plywood,....

But, for yer criteria, I'd search out some Black Locust, as it's a native weed tree in our areas,...
just a chore to find as Lumber,...

It's as rot resistant as P/T lumber,... Naturally,...

 

[Woodonglass]

Re: Western red cedar for stringers?

Just curious, as to your choice of wood as opposed to plywood as Bond-o suggests? I do understand the desire for rot resistance, however, Ext. Grade plywood, properly prepped and encapsulated in Resin and Glass, and then cared for and maintained in the correct fashion, will last for 30+ yrs. This should be more than adequate for your needs. It's lighter, more readily available, and has more structural integrity than lumber. If you research and study the threads here on the forum, you'll find that almost all of the restorations are using plywood for their stringers. The first link in my signature has some info that might be of interest to you.
This was taken from the Glen-L Boat Building Site, for your reading enjoyment
CEDAR, WESTERN RED
23 lbs. per cubic foot, 1.92 lbs. per board foot
Grown in the Pacific Northwest, the wood has narrow white sapwood and reddish-brown heartwood. It is rather soft and weak, shrinks very little, and the heartwood has good resistance to decay. The grain is uniform and straight although somewhat coarse and brittle. While often used for conventional planking, it is not highly recommended for this use. However, for veneers for use in cold molded hull planking, the material is excellent.

 

[chconger]

Re: Western red cedar for stringers?

Just curious, as to your choice of wood as opposed to plywood as Bond-o suggests? I do understand the desire for rot resistance, however, Ext. Grade plywood, properly prepped and encapsulated in Resin and Glass, and then cared for and maintained in the correct fashion, will last for 30+ yrs.

Interesting about plywood. I found wood in the boat when i opened her up, so I assumed that wood should go back in without thinking much about options.

I am very paranoid about rot, and will encapsulate it all with epoxy; But I also want to start with a rot resistant wood in the first place. Overkill yes; but I like overkill.

The softness of red cedar seems to be a drawback.

Back to ply, I have stock of 3/4 marine Mahogany ply. A quick calculation shows me that its my cheapest choice of rot resistant material compared to W.R.Cedar or White Oak.

So perhaps the ply....

When I am screwing the deck down into it, I will be attaching into the edge of the Ply. Not sure how well that works?

Cheers
Chris

 

[DeepBlue2010]

Re: Western red cedar for stringers?

IMHO, you can still use the red cedar if you “want to”. A great deal of the structural support function of a stringer is coming from the glass. Some factories even use all glass stringers with no core at all or foam core. Theoretically – at least – you can add layers of glass until the actual core becomes irrelevant to the strength of the stringer. For all practical purposes though and looking at it from a “need to” vs “want to” perspective, Ply will just do as good of a job. You also can get a really good protection with Poly resin, you don’t necessarily need to use Epoxy for good water intrusion prevention. You can if you want to, but you don’t have to since you will be glassing over the whole stringer. If you pre saturate your ply with poly resin – and let this cure - before you apply your first layer of glass, when it is time to glass, the thirsty wood will not suck all the resin out of your glass leaving the glass starving for resin which lead to weak bond to the core – the wood – and this is where the moisture find its way in. I can show you how much voids and delamination – separation of glass and core – I have in my stringers coming out of the factory, you will not believe it. Another common path for moisture to get to the wood is screws. In general, any screw you will insert in a boat need to be bedded in 3M 4200 or 5200. I wouldn’t screw directly to my stringers if I were you even if they were wide enough. I would add a brace of Epoxy coated cedar – I would use Epoxy here since I am not going to glass the brace and I will rely 100% on the resin for water proofing – to your stringers by gluing them with 5200 and mechanical fasters – stainless steel bolts and nuts – and use these to screw your deck to.

 

[Woodonglass]

Re: Western red cedar for stringers?

Epoxy is a great resin, and as you say you like Overkill and IMHO it is Overkill. Your boat is made from Poly and Poly will do a great job in restoring your boat @ about 1/2 the cost. The epoxy folks tout the better water resistance and strength of epoxy and while it's all true, Poly when applied properly provides more than ample strength and water resistance for boat construction. Never seen a Fiberglass boat made from poly suffering from water intrusion issues, other than blistering, and again that's usually caused from poor prep and application and NOT because of the actual makeup of the material. Marine grade plywood has multiple plys with very few voids and accepts fasteners extremely well. You will be pre-drilling and coating all of the holes and fasteners with resin so there's not much to worry about in that area. Your boat is 23 years old and suffers from MFG's "Get it out the Door" syndrome. You will do a much better job at glassing the stringers , transom and deck. I expect also, since you have done all the hard work, you will care and maintain the boat much better than the PO's. This will play a major factor in the longevity of the boat in the future.

 

[chconger]

Re: Western red cedar for stringers?

I wouldn?t screw directly to my stringers if I were you even if they were wide enough. I would add a brace of Epoxy coated cedar ? I would use Epoxy here since I am not going to glass the brace and I will rely 100% on the resin for water proofing ? to your stringers by gluing them with 5200 and mechanical fasters ? stainless steel bolts and nuts ? and use these to screw your deck to.

Yea! Now that sounds perfect. Then I am not dealing with the edge of the ply, any potential for failure of a decking fastener / or seal does not directly endanger the stringer.

More I think about the ply, the more I like it. I know I will have a dead straight edge on top as well; no chance for bow in the wood.

Thanks!!

 

[Woodonglass]

Re: Western red cedar for stringers?

I presume you will be using a couple of layers of 8-10 oz cloth to attach the stringers to the hull correct?

 

[chconger]

Re: Western red cedar for stringers?

Yes I havent got there yet in my head, but I am planning to wrap them / attach them with what ever is appropriate. Sounds like your saying 2 layers of 8-10oz is good to go.

 

[Woodonglass]

Re: Western red cedar for stringers?

If you decide to stay with the epoxy then yes i think that would be appropriate. You could step it up to a layer or two of 17 oz biaxial cloth if you want to do the "OverKill" thing. If you go with Poly then the first link in my signature has all the info on materials and installation techniques.

 

[chconger]

Re: Western red cedar for stringers?

Just checked my local marine store web site and they carry only 6oz cloth or 24 oz roving. If i went 6 oz can i make up the difference by going 3 layers. Or does it "not work that way"

 

[DeepBlue2010]

Re: Western red cedar for stringers?

You need to decide on the type of resin first. I would - and a lot of restorers here - use 1708 Biaxial cloth. There is another version of this fabric - without the .08 CSM in the back - for use with Epoxy. I believe this is the best fabric for the job. 2 layers are plenty but 3 would be good overkill. BTW, both of us like overkill This is a good online source for your materials http://www.uscomposites.com/

 

[Woodonglass]

Re: Western red cedar for stringers?

If you decide to go with the Epoxy then using 3 layers of 6 oz cloth on the stringers would work. You would start with small strips and get progressively larger moving up the wall of the stringer.

 

[chconger]

Re: Western red cedar for stringers?

If you decide to go with the Epoxy then using 3 layers of 6 oz cloth on the stringers would work. You would start with small strips and get progressively larger moving up the wall of the stringer.

Thanks! I am on my way then.