Timber varieties and moisture content

Don't you people read what I say!.

 

Sure we listen, but it wouldn’t be a forum if we didn’t add our $.02.

Gary

 

Will;

The Gougeons started using 1/8" WRC veneer to build racing sailboats. At the time foam cores and glass were heavy, cold-moulded wood was the way to go light. This was late 70's. A Farr 36' had a skin 1/2" thick total, four diagonal layers, on closely spaced spruce longitudinal stringers. The planking was sheathed with about 6 oz. glass, very light. But those stringers were a real pain, especially when the goop started running every-which-way. Plus lots of man-hours in all those layers.

Then people started to recognize the value of the glass sheathing. There is a good piece on this in Professional Boatbuilder #69. You can use the wood in strip plank form to be a core but also to add considerable longitudinal stiffness, due to grain orientation. Cross grain and hoop strength can be easily carried by thin skins of biaxial glass. Low man hours and clean, stiff structure. I believe Scott Jutson uses this construction for low budget and competitive racing sailboats.

Brett;

Rybovich used to use Philippine Mahogany in three diagonal layers over solid fir longitudinal stringers. They use a single 20oz. sheathing of glass. Or at least they did in the mid 90's, could be different now.

In the late 80's I did a cruising sailboat to be cold-moulded in Tasmania of local woods. I believe planking was to be four layers of Celery Top Pine. The framing was all to be laminated King William Pine. The boat may be out sailing by now. The builder sent us some samples of the wood, lovely stuff!!

Scheherazade at 154' is cold-moulded of fir longitudinal inner and outer layers over diagonal WRC. Total skin thickness is 3.5". Inside layer is 3/4" T&G fir running fore & aft, then four diagonal layers of 7/16" WRC, then 13/16" fir running fore & aft, then two layers of fiberglass. All layers a vacuum-bagged together.

All the best, Tad

 

Huh!! I was going to mention King Billy (William) Pine - but didn't think anybody would've heard of it. I have a model that my father built out of the stuff 40+ yrs ago - you're right it is lovely stuff.

What was the boat going to be called - and if you can tell me (client confidentiallity stuff...) what was the client's name, I might know them - and the boat.....

 

Will;

I didn't ever hear a name, she is 46' LOA, a small Whitefin with trunk cabin. 7/8's sloop rig. The owner/builder was a real boatbuilder, not sure, but I think in Hobart. His name is Hugh Wardrop. Seems the last photo's I saw were of the hull right side up. But that was years ago.

Tad

 

Guys ,

I was actually refering to Wills comment about Western Red Cedar and my comment re tasmania was directed at will being a 'Bass Strait Islander". lol Surprised at Will not mentioning Huon Pine. Sure it takes 800+ years to grow a decent tree but it doesn't rot. The folk on the west coast down there love the stuff but is very expensive since they can't cut it down anymore.

I am currently working on a 84' cruising yacht being built using strip plank kauri with triaxial/epoxy skins. Total skin thickness is about 1.5". Deck & Pilothouse are balsa sandwich. Should be in the water late next year.

Brett

 

Sorry Brett, didn't mean to pass over you 1st post - my query was really aimed at those in the US, as the questions are part of one of my Westlawn lessons. I'm fairly familiar with all the Aussie stuff....
Oh - and you're right - there simply ain't no better boat building timber than huon pine. There are some fairly substantial stocks about - you just gotta know who to ask. Most is stuff felled before Hydro dams flooded the various rivers.

Tad - if it's a Hobart boat, then I'd definitely know it - small world as they say

 

Will, Apology accepted.
I was in strahan (spelling) about two years ago and visited te Huon pine mill there. The guy basically said the guvment owns the trees felled before the dams were filled and hands it out each year. Other than that you have to wait outside the world heritage areas and catch the tree's if and when they float down the rivers or accidently stumble across a sunken log and harvest.

You probably know more about this than I do since you are a local.

The stuff smells divine too...

 

Will & Brett;

Huon Pine was another wood to be used in the Wardrop boat above, I'd forgotten about that.

Brett,

1.5" sounds thin to me, DNV? Lloyd's? How do you deal with the inside skin? Does it start and stop at bulkheads, or are all internals added after the hull is turned over? I've always been fixed on the idea of including bulkheads and floors in the setup, so inside skins aren't really an option.

Another method would be to put on the first layer of planking, then the inside glass or Kevlar, then finish planking and add outside skin.

Whitehawk and Whitefin (both about 90') have skin thickness about 2.25"-2.5" in five and six layers. Undoubtedly overbuilt but nice stiff hulls. But no triaxal glass.

Tad

 

Tad,

This particular boat is a blend of new and old with continuous longitudinal keelson and sheer clamps. The hull was built upside-down over the bulkheads and temprary cnc cut frames.

Kauri planked (chosen by availability) longitudinaly and glued to sheer lamps, bulkheads and keelson then glassed with multiple layers of triaxial. Entire assembly was then turned over and each compartment glassed with triax. and lapped onto the bulkhead grounds. I do not believe that these joints will present a problem. Additional frames of DB/UD were then fitted as required on foam formers to support the panels along with the deck and sole connections.

Deck was built using prefabricated balsa panels and attached to prefabricated cambered db/ud beams. Quite light really.

The entire design is engineered to AS 4132 which is a commercial vessel standard. I could go on and on etc but really need to do some work. Feel free to ask me more. Boat is being fit out as we speak.

 

Bloody good looking boat Brett! Interesting rig too - If you care to I'm sure we'd love to see some pics as she comes together....

 

Will,

if I get more interest from some of the others I might start a new thread with it so i don't hijack yours. I have plenty of photos but not too many that are digital so i would be happy to put up a few if there is interest.

Brett

 

Thumbs up from me!

 

Oooh, pics! Goody! More, please, Sir.

 

Brett;

I don't think it's a real hijack, just a bit of drift.

Nice rendering of a good looking boat. Some questions, not to be critical, only curious. Interesting rig, ketch size foretriangle with schooner (or staysail ketch) stuff aft? Is the trysail on a wishbone? You have three furlers forward and the outer one is a blade/100% jib? The inner is a staysail, what's the middle one?

You mention continuous longitudinal keelson and clamp, are they laminated wood? Are all floors foam cored? You mention flanging the inner skin on to the bulkheads, would these compartments be small (say 2m long) or is this just 4-5 major bulkheads? Very interesting!!!

I have not found anything on AS 4132 yet, does that incorporate the latest ISO construction scantling rule?

Sorry for all the questions, you really need to get some work done.

Take care, Tad