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Shipyard Memories #20: The Harbour Ferries: Stitch and Glue Construction.

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Blog entry by shipwright posted 09-10-2011 04:22 AM 2999 reads 3 times favorited 13 comments Add to Favorites Watch
« Part 19: Something Really Cool Just Happened to Me on LJ's Part 20 of Shipyard Memories series Part 21: The Jig, Patterns, and Hull Glue Up »

This is the fourth and last blog on the different styles of construction that I have used in wooden boat building. Preceding blogs have covered Carvel Plank construction, Framed Plywood construction, and Cold Molded Construction. This one will cover what has become known as “Stitch and Glue” style. It is generally associated with but not exclusive to use with plywood.

I wasn’t as into photographing the progress then as I am now, in fact if I hadn’t decided to build two boats in the winter of 1994, in anticipation of the Commonwealth Games coming to Victoria that summer, I would not have hired help that year and likely wouldn’t have any photos at all. Many of the photos will feature Jim Kennedy who helped me that winter building Harbour Six and Harbour Seven.

I also apologize for not having photos of a few key components (like the stitching) but I will try to explain well enough to give you a clear picture of how it’s done.

There are several ways to approach stitch and glue but most start with the various components of the hull being cut from patterns either supplied by the designer or created from a full size lofting from the plans. These components are then assembled by stitching the adjoining edges together whereupon the hull takes on three dimensions as the curved edges are brought together.

These boats are a little large for that so I built a jig from the plans and took the patterns from the jig. We’ll get to all that soon enough but for now let’s start at the beginning. The first order of business in building a twenty foot boat in this style is to acquire twenty four foot plywood.

I always scarf my plywood with an 8:1 scarf and cold cure epoxy. There is no need to back this joint with anything because it is as strong as the rest of the plywood. The first thing you need to do is set up a scarfing station that will support a stack of plywood and has at one end a solid, flat wood surface. Then you stack as many sheets as you will be scarfing in a staggered pile with the offset equal to 8x the plywood thickness. In our case with 3/8” plywood the offsets are 3”. The sheets can be tacked together with a pin tacker staying away from areas that will be planed off.

Next is simply to plane off a flat surface in a plane from the lower edge of the bottom piece to a line 3” back from the upper edge of the top piece. Keeping the glue lines in the plywood straight will ensure an even cut and when you are finished you will have 3” scarfs with knife edges. As we were scarfing three pieces to get 24’ some of the pieces were flipped end for end and done again to give scarfs on both ends of the center pieces. By the way, that’s a Skil 100 power plane, the best power plane ever made IMHO. I guess you could use a hand plane if you were a purist, but it takes about ten minutes with the 100.

Once the contact faces are cut the pieces are set up on your custom designed 4’ by 32’ scarfing bench and glued up. In this shot Jim is spreading epoxy on both sides of a joint. Under the joint is a strip of polyethylene which conveniently does not stick to epoxy (or vice versa).

Once the glue is spread, one sheet is flipped over and the scarfs are aligned. A couple of tacks away from the joint will assure that nothing moves. Then more poly is placed over the joint followed by a strip of 1/4” plywood 3” wide exactly over the scarf. In this photo Jim is pressing down with the air stapler until he sees glue squeezed out of the joint (under the poly) before firing a pattern of staples to clamp the joint. When both scarfs are stapled up the next set of three sheets is laid up in the same manner on top of the first one. This is repeated until all the pieces are done. When the glue sets up the plywood strips are pried off and if you’re living right, most of the staples come with them.

This shop was 40’ x 60’ and was built on our property specifically to build and do annual maintenance on these boats, so the scarfing bench was a high priority.The last photo shows the shop set up I used for scarfing. The plywood rack was at one end of the bench (see first photo) so pieces could easily be pulled out by one person and there were two 4’ infrared heaters located 8’ apart that could be lowered right down to a couple of feet above the scarfs to cure them overnight. (note the snow outside).

That’s it for tonight, next time I’ll cover the jig, patterns and hull assembly.

Hope you’re enjoying this as much as I am.

Comments, critiques and especially questions are encouraged.

Paul

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/



13 comments so far

View Napaman's profile

Napaman

5365 posts in 2822 days


#1 posted 09-10-2011 04:33 AM

NOooooooooooooooooooooooooooooo….........say it aint sooooooooooooooooooo!!!!!!!!!! The last blog??? Just had to say that…lol…now I can go back and read…

KEEP EM Comming buddy!!!!!!

-- Matt--Proud LJ since 2007

View Napaman's profile

Napaman

5365 posts in 2822 days


#2 posted 09-10-2011 04:55 AM

ok…that is a nice entry…really good…I guess I can forgive you ending the series—-this way you can focus on your boat building books and videos for dumb first time builders…

With 1/4” sides—-I will be joining to pieces about 8’ in length by 2’ wide…will this mean my scarf area will be 1.5 inches? seems like the “overlap” should be longer…?

-- Matt--Proud LJ since 2007

View sandhill's profile

sandhill

2128 posts in 2668 days


#3 posted 09-10-2011 05:26 AM

Great blog Paul keep it coming I love it.
Thanks for showing us

View shipwright's profile

shipwright

5295 posts in 1542 days


#4 posted 09-10-2011 05:44 AM

Matt, Here in Canada anyway, eight times 1/4= 2” :-)
If you can get the surfaces planed nicely so that the contact is good, then yes, 2” is as strong as the rest. You should be using something in a five ply although three will do in a pinch.

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/

View Lee A. Jesberger's profile

Lee A. Jesberger

6698 posts in 2724 days


#5 posted 09-10-2011 12:58 PM

Hi Paul,

I know I’m enjoying it. I had no idea you could join plywood like that, and the idea that it’s as strong as the rest of the sheet is pretty amazing.

That was quite a shop you built.

Lee

-- by Lee A. Jesberger http://www.prowoodworkingtips.com http://www.ezee-feed.com

View patron's profile (online now)

patron

13156 posts in 2086 days


#6 posted 09-10-2011 01:23 PM

as usual
learning these things from you

is always worth knowing

something we can count on
when we need them

thank you

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View BertFlores58's profile

BertFlores58

1646 posts in 1667 days


#7 posted 09-10-2011 01:58 PM

Why not include in the class series… Maybe this is more than a class.. I have to begin compiling these because I am losing trace for those words used. Only shipbuilding knows… or sailors.. like “scarf” then stitch.. just like a tailor … LOL. I really love this blogs where there are so much to learn.
Thanks and keep it going.

-- Bert

View Bluepine38's profile

Bluepine38

2953 posts in 1830 days


#8 posted 09-10-2011 06:11 PM

I have seen scarf joints used on boards, and laminated beams, but this is the first time on plywood. If you
are as good and precise as you obviously are, they would be OK, with someone like me, I would have to
practice on quite a few joints before I attempted the critical one. Thank you for sharing.

-- As ever, Gus-the 76 yr young apprentice carpenter

View Napaman's profile

Napaman

5365 posts in 2822 days


#9 posted 09-10-2011 06:11 PM

lol…2” south of the border too…i missed the 8x part when I wrote that…thanks!

-- Matt--Proud LJ since 2007

View shipwright's profile

shipwright

5295 posts in 1542 days


#10 posted 09-10-2011 06:40 PM

Lee, The shop was 32’ by 60’ free span with a 12’ ceiling and an 8’ roof extension on one side. ( I got a deal on 32’ trusses) The inside end of the trusses was supported by a beam and a few posts.
The bench shown was across the 40’ end opposite the doors (12’w x 12’ h) with the plywood rack in the 8’ extension. It was a great shop.

Bert, hard to make one of these blogs into a class. You’d have to build a whole boat.

Gus, I’ve used these joints for many years and they have been subjected to huge abuse (see dockings above) and I’ve never seen one fail.

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/

View stratman's profile

stratman

9 posts in 1204 days


#11 posted 09-10-2011 07:27 PM

I am new to this site and am excited to see your informative blog. great!! I am a yacht restorer in San Rafael, Ca. I’ve never built a boat from scratch, but, rebuilt plenty of wooden boats. I had an old 30’ motor sailor back in the 80s’. Glass over ply. It had the same technique but was made with two laminated 3’4’ marine ply. after 39 yrs. the ply was still sturdy and sound. Glass over ply turned out to be a very, very good way to make hulls indeed. never leaks and if you punch it with a rock or something. it is easy to repair and be on your way. After I sold it in 1990, it was neglected to distraction. It was finally cut up and hauled off to the scrap heap. The hull was still in great condition. unbelievable. I presently own a 1928 Lake Union Dreamboat by Carl Rathfon. Great boat.
Fir and Mahogany. No rot in hull or decks. After dis-assembling an re-assembling whole areas of boats. Chinese puzzles are easy. I also owned a Newporter 40’ and sailed it to Isla Bella in Brazil. It is at the Yacht club on the island. The Brazillians still make a schooner called “Saveirro”. they are still popular among the wealthy. big and beautiful they are. please remember a little prayer for the victims and heroes of 9/11 and for ourselves in this most trying of times. Bless you all.

-- stratman

View itsmic's profile

itsmic

1419 posts in 1863 days


#12 posted 09-14-2011 01:58 AM

No questions Paul, Just a big “Thank You” for all Your geneous contributions, I probably will never build a boat, but, this information is invaluable and inhances the old knowledge bass, having a bonified expert giving free advise and info is like hitting the lotery, thanks Paul

-- It's Mic Keep working and sharing

View LittlePaw's profile

LittlePaw

1571 posts in 1823 days


#13 posted 09-17-2011 05:15 AM

It’s getting more and more interesting by the post! I’m not planning to build a boat, but the knowledge I gained from your posts will come in handy in the things I’ll be making. Thanx, Paul.

-- LittlePAW - The sweetest sound in my shop, next to Mozart, is what a hand plane makes slicing a ribbon.

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