PDA

View Full Version : white oak, fir or mahog?



denis,qc
07-06-2006, 12:51 PM
need your comments about what wood to use for framing,chine,sheer,stringers,battens.
the boat is a 19``runabout v-8 engine
price for the mahog is almost twice the oak...
any help will be appreciated...

Nicholas Carey
07-06-2006, 01:46 PM
Building new, or repairing/restoring?

If it's the latter, I'd be inclined to use what was used originally.

If you're building new, I'd be inclined to go with what the designer specified in the plans. If I was going to make a substitution, I'd look at the Wood Handbook (http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.htm) (our Tax Dollars at Work) and pick a wood with similar engineering, mechanical and durability qualities.

White oak is traditionally a framing wood for boats and it would make a fine frame. It's also local to [southern] Quebec, I believe.

denis,qc
07-06-2006, 02:46 PM
yes it`s a new one. I like the strength of white oak but the problem I`ve read is with epoxies. Some boatbuilders love w.oak and others seems to have problems with w.oak+epoxie.
what i`d like to do is using w.oak for framing, doug.fir for chine,sheer and battens

Tar Devil
07-06-2006, 02:58 PM
White oak holds fastenings well. Fir and mahogany glue well. What do your boat plans require?

Later,

Phil

denis,qc
07-06-2006, 03:07 PM
suggested lumbers are mahog, fir or spruce(sitka). I can`t find sitka with dimensions I need. I can get african mahog and fir. White oak is less expensive and a lot more abundant around here...

Tar Devil
07-06-2006, 03:25 PM
Denis, why don't you tell us what you are building?

denis,qc
07-06-2006, 03:38 PM
hankinson`s design. tahoe 19`

Tar Devil
07-06-2006, 03:43 PM
So, this is a cold molded or strip planked boat?

Robmill0605
07-06-2006, 03:50 PM
I think that the answer to your question lies in the method of construction that you intend on using.
If you are going to build her in the traditional mammer i.e. batten seam, then use white oak.
If you are going to build her cold-molded the mahogany works easily, takes shaping well, finishes better and the holding factor of the fastenings are minimal as it is composite/monique construction.
I used mahogany on my 16' hacker as I cold-molded.
[IMG]http://i55.photobucket.com/albums/g148/robmill54/Scan0003_0003.jpg (http://s55.photobucket.com/albums/g148/robmill54/?start=#imgAnch5)

denis,qc
07-06-2006, 03:50 PM
cold molded

Tar Devil
07-06-2006, 03:56 PM
What Rob said.

Fir or mahogany will be kinder to your tools, shape easily. Since it's cold molded, glueing kinda takes precedence over fastening, hence I'd steer away from white oak.

My .02 worth, anyway.

Later,

Phil

denis,qc
07-06-2006, 04:01 PM
somebody got any experience with white ash??

Robmill0605
07-06-2006, 04:59 PM
If you are going to cold mold then take a good look at the construction methods methods used by Van Dam. I would of saved myself a LOT of time by using his methods. First, he uses mahogany as I did. Since you are cold molding then go the extra for mahogany. The overall cost increase is minimal compared to the overall project. The mahogany will bond better than oak.
Next, I cut notches in all my frames and faired into them. Van Dam does not notch the frames. Instead he deducts the thickness of the battens and the planking thickness in the lofting, and lays the battens directly over the frames. If you are using Glen-L plans and are using full size patterns you can still do this. This method is fast, and accurate.
Do NOT use Okuume ply. It will rot and I recommend you use Sapele mahogany for your laminates. Glen-L strip planks?? I'm not sure.
Anyway since I've been down this road I'll be happy to answer your questions if you PM me.
Here's a link to his site.

http://www.vandamwoodcraft.com/

Bob Cleek
07-06-2006, 10:04 PM
There's no reason not to use doug fir for the underlayment and mahogany for the top veneer if you are cold molding. I'd stay away from oak for the weight issue, if nothing else. Epoxy weighs a bit and you don't want your boat any heavier than she has to be, particularly if you are putting an eight cylinder engine in her! (Does it come with wings?)

denis,qc
07-07-2006, 09:12 AM
I took a look at vandam, I was impress by the small dimension of the frames on ImpshiII . On my plan the frames are 3/4 by 3'' wide.
So if I go with vandam`s way my battens are 5/8 deep plus 3/8 wood layers. That means instead of sawing 3'' wide frames I`d go with 2'' plus 5/8 battens and 3/8 wood layers.Is that right??

Robmill0605
07-07-2006, 10:10 AM
I took a look at vandam, I was impress by the small dimension of the frames on ImpshiII . On my plan the frames are 3/4 by 3'' wide.
So if I go with vandam`s way my battens are 5/8 deep plus 3/8 wood layers. That means instead of sawing 3'' wide frames I`d go with 2'' plus 5/8 battens and 3/8 wood layers.Is that right??


Yes, remember that by notching the frame you weaken it by that amount anyway. If you are cold molding the strenght in the hull is from the sum of all the parts being bonded together as a whole structure,instead of relying on fasteners. The frames are really there to determine shape.
I used three layers in my hull each 1/8 thick. The final layer was applied 3/8 thick fore and aft as in regular construction for a total of 5/8.
Don't forget to gusset your frames. If you have the Geougeon brothers book on cold molding it shows the process.
You have to change your thinking a little cold molding.
Here you can see the inner layer as I plank up the hull. They are fastened with narrow crown stainless staples which will stay in the hull. The plank is being wedged in plank while it is fastened with staples.
Van Dam used a screw with a washer and thenremoves it, countersinks, and bungs.


[IMG]http://i55.photobucket.com/albums/g148/robmill54/boatplanking6.jpg (http://s55.photobucket.com/albums/g148/robmill54/?start=40#imgAnch47)

denis,qc
07-07-2006, 11:43 AM
Rob, I have the plans of garwood speedster 16` 1935. It looks a bit similar to your hacker. Are you building with a plan? What engine will go in that beauty? Is it a two seater? Just curious...

emichaels
07-07-2006, 05:41 PM
somebody got any experience with white ash??


white ash is not very rot resistant.

Robmill0605
07-07-2006, 09:43 PM
Rob, I have the plans of garwood speedster 16` 1935. It looks a bit similar to your hacker. Are you building with a plan? What engine will go in that beauty? Is it a two seater? Just curious...


They are very close. My boat is a 16' Hacker Gentleman's Runabout about 1922. It's a two seater. I'm planning on a Merc cruiser engine [v6]If I had it to do over, I would have built his 21' runabout. The smaller boat is just as much work, and is actually harder to build because of the extreme flair in the bow. Steaming these in way the only way to go. I made patterns of each plank before commiting my precious book matched mahogany.
The 19' is a good size to build.

Here is the plan
[IMG]http://i55.photobucket.com/albums/g148/robmill54/400076.jpg (http://s55.photobucket.com/albums/g148/robmill54/?start=#imgAnch1)

This is the boat so far, I'm just about finished with varnishing the interior and then the deck will be next.

[IMG]http://i55.photobucket.com/albums/g148/robmill54/boatplanking7.jpg (http://s55.photobucket.com/albums/g148/robmill54/?start=40#imgAnch48)

denis,qc
07-07-2006, 09:56 PM
Well Rob I must say that I saw a tree right in front of your house that we really dont`see at all around here!! Are you in Hawai or Florida???
Here in Quebec we have maple and oak....What`s the widnts of your planking?? Seems to be somewhere between 4 to 6 inches??

Robmill0605
07-07-2006, 10:17 PM
Lol, I'm in Ft Myers Florida on the Gulf coast. I lived in Maine for a long time so I don't miss the winters, but I do miss the abundance of good wood and the great craftsmen/boatbuilders in Maine. I've had to ship just about everything but hey, it's paradise here so I'll ship it!
The planking varies in width. Look at your plans and the middle of each batten will be the plank seam. I used a batten to get a fair curve in lining off the hull for planking. As you plank the hull with the diagonal layers be sure to transfer the location in pencil of all the internal structure so that you do not lose track of where the frames and the battens lie. VERY important. If you look closely at the first picture you can see the pencil lines on the inner planking.
Just remember the old adage, if it looks right------- it's right.

Ron Williamson
07-08-2006, 05:47 AM
Tamarack is a reasonable substitute for Douglas fir.
R

denis,qc
07-08-2006, 11:22 AM
Ron,where did you find tamarack? First time I hear of this one. Even Noah`s doesn`t list it.

Nicholas Carey
07-09-2006, 02:41 PM
The scientific name for North American tamarack is Larix laricena. It's also known in this country as larch and hackmatack (an Abeneki word meaning "the wood used for snowshoes"). European larch is Larix decidua. Japanese larch is Larix kaempferi.

In Quebec, you'll likely find it called, in French, Mélèze laricin (European larch is called Mélèze d'Europe.)

It's good wood for boat building and it's local to Quebec. This is the range of L. laricena

http://www.nearctica.com/trees/conifer/tsuga/mLlari.jpg

Here's a page describing it, from the US Forest Service Sylvics Manual: http://www.na.fs.fed.us/spfo/pubs/silvics_manual/Volume_1/larix/laricina.htm

If you look at the US Forest Service's Forest Products Laboratory's book, The Wood Handbook: Wood as an Engineering Material (http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.htm), you can find more information on it. You'll find it's quite comparable to Douglas fir.

denis,qc
07-09-2006, 10:16 PM
OK, so what`s better, use tamarack(LARCH) or mahog??

Ron Williamson
07-10-2006, 05:18 AM
I say Tamarack, because it's cheaper and local.
R

denis,qc
07-10-2006, 06:27 AM
Ron, have you tried boatbuilding with tamarack??

Ron Williamson
07-11-2006, 04:51 AM
Ha,you got me.
No,but I've got some logs in my yard that haven't been touched for a few years.They are still decent,aside from some checking and the sapwood going bad.On par with the white cedar and walnut that is also there.
Everything else,maple,ash,balsam,spruce,is going bad.
One of my partners made flooring,stairs and mouldings out of it,last winter.
R

Bruce Hooke
07-11-2006, 08:04 AM
Keep in mind that boats designed to plane are much more weight sensitive than displacment craft. For this reason you should be cautious about substituting a heavier wood in place of a lighter one.

denis,qc
07-11-2006, 07:28 PM
Well, after extensive search around, I can`t get larch wide enough for the frames so I`ll probably go with afric.mahog for framing. Correct me if I`m wrong, but in my mind doug.fir is easier to bend for battens,log and sheer?? Can I go with two kinds of wood ??