View Full Version : Help picking out 4x8x20 Douglas Fir to Resaw for Boat Lumber

04-14-2015, 09:22 PM
I could use some guidance on picking out 4x6 & 4x8 20' Douglas Fir to be resawn for my Wharram Tanenui build.

It's very beautiful wood. No. 1 & Better, air dried, straight grain. I can pick thru & choose my pieces. I'll need about 12, 4x8x20 or 16, if 4x6x20. Or combination of the two widths.

I saw them a few months ago when looking for a house project. Was amazed at the quality of the beams! Straight, no knots at all, really nice lumber, it looks like cabinet grade wood.

When I get the 4x6/4x8 home I'll resaw them a fat 1/6" over size & let them dry & relax for a few weeks. Then finish them to final dimentions.
Most of the sizes needed are "x2" & 3", 2"x2" and a few pieces for crosbeams 5-" wide or so.

I know I want grain that runs a long way before crossing 1" out of line.
But how straight is straight enough?

I'm guessing they will be flat sawn mostly. I didn't pay real close attention when was there last.

What are some likely ways they will be sawn & what do I want?

When I resaw them I can cut them to optimize grain direction. But don't know what that is!

If anyone has links or any help, ideally specific directions it would be most helpful and appreciated!

I have been a contractor for many years. It's just laying out & resawing for optimum strength for boat building is new. Not resawing lumber.

Cheers, Allen

04-14-2015, 09:48 PM
A Tanenui ?

Please start a build thread when the time comes, Tanenui is one of my favourite WorryCats and I'd like to see it come together .

I can't help with your fir selection.

04-14-2015, 10:20 PM
I'm going to do a build thread and a blog, about the Tanenui build, not me! Lol The reason for a blog about it is I'll put more pics & more detailed construction pics than would want to put on a build thread.

Mostly because there isn't much out there on the Tanenui as they were more popular before the internet.

Some basics on her is Douglas Fir lumber, Okoume 1088 Marine ply it's mostly 9mm, System Three SilverTip laminating epoxy & SilverTip GelMagic adhesive, 6oz glass on all the exterior corners, hull to deck, hull to keel, hull to bow & stern posts, cabin ect as Xynole has to much stretch for this application

With Xynole sheathing on everything exterior, two layers below water line. Only doing this because here on Big Island HI, there are lots of rocks. So she will get banged into them sooner or later. If not for that I would use one layer below water line. 8 stave Doug Fir mast.

Sewing the sails using SailRite kit.

Raising deck to gunnel level, with gunnels. Most likley (99%) stretching her 24", 18" in center between bulkeads 2 & 3, 6" between bulkead 1 and 2 and 6" between bulkeads 3 & 4.

Building her with JWD Tiki style Crossbeams & lashings, using JWM upgrade drawings specifically for the Tanenui and their Sailwing upgrade drawings also.

Cheers, Allen

Measures Once Cuts Twice
04-15-2015, 07:09 AM
Good luck, sounds like a great project!

( and commenting so that I'll see all the good wood info too!)

Jim Ledger
04-15-2015, 07:30 AM
How do you intend resawing the lumber? Are you doing the sawing yourself or having it done for you?

Gib Etheridge
04-15-2015, 11:32 AM
There aren't many places in a boat where vertical grain isn't the best choice. How about some photos of the beams? Upload the photos to Photobucket then copy and paste them into the reply box. Close ups of the ends will help, but full length showing number and size of knots counts to.

Looks like a hard chine catamaran, yes?

https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcQnA5eZrW9ts5k1jRoaCbo7LQUrWyf-NK9WAjH8OPLDcA6-_Rk (http://www.google.ca/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRw&url=http%3A%2F%2Fwharrambuilders.ning.com%2Fphoto% 2Fvinces-tanenui-2%3Fxg_source%3Dactivity&ei=KJIuVf6VFJDsoATatoCICw&bvm=bv.90790515,d.cGU&psig=AFQjCNGUnllA9a71BZkbBoiR4dVgNZWO7Q&ust=1429201796141026)

Kevin Moroney
04-15-2015, 12:02 PM
So envious! Could have used some of that myself. Where did you find it? Was looking in FL for a full size 4x4 x 20 for a boat mast and it would have been easier to win the lottery!

04-15-2015, 01:41 PM
How do you intend resawing the lumber? Are you doing the sawing yourself or having it done for you?
Curious about that myself.

04-15-2015, 04:59 PM
I was quite surprised to find this kind of wood here on Big Island HI. Let alone for this price. 4x6x20 $57 & 4x8x20 $76, both S4S. Not on sale usual price.

As as for resawing, my usual way is set them on stable saw horses wide side down. Measure & mark for thicknesses of 'slabs' wanted including extra width, 3/32 to 1/8 to run thru planer afterwards for final final size & to make perfect surface on both sides. When flipping it over pull measurements from same side of piece.
If done carefully, the cut will be nice enough that it can be ran through a table saw. A good cut is more important on the pieces that are resawn on both sides.

I make a straight edge out of aluminum angle a couple feet longer than beam. Drill & counter sink screws for splice pieces to make guide long enough. If I have more than one piece of lumber I lay it next to one I'm cutting so it supports the off side of saw plate. I like a worm drive circular saw. The blade is on left, more powerful & easier to push straight tight along guide. I use Diablo saw blades. They work better than any other I've used.

Make first cut, turn it over, start cut at opposite end to line up with first cut. Set saw cut depth to cut just past center, ⅛" or so.

Repeat for rest of cuts. If measured carefully & guide set properly the cut will be almost flat with no offset.
It's important to cut with slow & with even pressure. If wood is wet or sticky and won't clear sawdust out of cut well, set saw depth shallower aund make multiple cuts.
I prefer to make the cut in 1 pass if possible. Use new blades, if one starts to act at all dull, use a new blade. The blades are cheap & using a blade that is even a little dull causes problems, especially with these thin kerf blades.

If I need to cut across the wide direction ie... across the 8" direction because of grain orientation, cut it to width needed from the 4" side then cut thru the other direction (what was the 8" before cutting the width needed).

if I don't need pieces 20' long, after I figure out what size pieces (width & length) I cut 20' to shorter lengths & run them thru table saw with out feed, finger boards & a helper.

Does any of that make sense?

I won't be in Kona for a week or so. When I go I'll get some pics of end grain & length ways grain runout. I haven't looked carefully at the grain orientation & runout since decided to build the Tanenui.

Il'll post pics of setting up & resawing them. It's going to be a while yet before I'm ready for it.

Cheers, Allen

04-15-2015, 05:41 PM
I'm not sure what it would be considered, I'm guessing not hard chines, it's a deep V hull. The hull sides go from deck to keel in one sweep. I'll see if I can figure out how to post pics.

Cheers, Allen