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Shipyard Memories #14: Cold Molded Planking

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Blog entry by shipwright posted 02-16-2011 07:43 AM 4919 reads 0 times favorited 14 comments Add to Favorites Watch
« Part 13: Two Cape Scott 36's: Cold Molded Construction Part 14 of Shipyard Memories series Part 15: Rolling Hulls Over and Pouring Lead Keels »

I have to apologize for my lack of a lot of photos of this stage. I guess it just seemed to boring to take a lot of photos at the time. Anyway there are enough to give you the general idea.

The first layer in this style of cold molding is applied on a diagonal as shown below. The exact angle is found by making several trial bends in different parts of the hull. The one that allows the easiest bends in the greatest number of places is the one to choose, if that makes any sense. This layer is epoxy glued to the stringers and bulkhead edges but care is taken not to glue the edges of adjoining planks together. This is because at only 1/4” thickness they will bend slightly differently and will not align exactly with each other. If this hull looks different to you,that’s because it is. This is Stevador, with it’s higher sides aft. I didn’t have any early photos of planking Olfara.

This is actually the third layer but for a moment, think of it as the second. The second layer is epoxied to the first and edge glued to it’s neighbors and as the layers are drawn together with sheet metal screws, any high and low plank edges in the first layer are brought into line. As the planks are snugged up together, excess glue fills the joints between the planks in the first layer and everything levels out nicely. The sheet metal screws are removed and re-used and as you can see in this photo the holes left behind are filled in the third layer. In the first and second layers this is not necessary as glue will be forced into them when the next layer is squeezed down on top of them. The piece nearest us in the photo is being temporarily held in place by loosely fitting cleats so that it’s far edge can be scribed to perfectly match the plank behind it, already glued down. That scribe line will be cut on the band saw and will then fit snugly against the previous plank. The other side will remain straight and the next piece will be fitted to it and so on down the hull.

This picture was probably taken at the same time as the last one but from further back. It shows a good view of the hull with two layers finished and the third started. These are the easy parts. It gets a little trickier around that stern.

The view from the bow after planking is complete. The stem and keel areas have been planed down ready to accept further laminations to finish off the shape.

This is the same thing except from the stern. Here the centerline has not yet been planed off. In the stern where the shape is extreme, the difference in planking is the amount that gets trimmed off from the scribing. Some of these pieces will be quite wide in the middle and quite narrow on the ends. They may also need to be narrower pieces to start with than in the forward and central areas.

!

I’m going to toss in a few photos here from planking my own boat “Friendship” http://lumberjocks.com/projects/37786 just to show another method of cold molding. This one is my own modification of the “strip plank ” method where a layer of thicker strips is first laid up over temporary molds and is then covered by thinner diagonals. My modification was to shape my planks in the first layer more like carvel planks instead of using many many, more narrower strips as is usual in this method. I used a bead and cove edge to keep them aligned and escape the very labor intensive edge fastening used in strip planking.

Here she is with the first longitudinal layer complete.

The first layer here was 5/16” followed by two opposing diagonal layers of 1/8” each. Now that’s a tough stern to plank! It doesn’t look too tough here but think about the first layer.

This method produces a hull that is completely clean on the inside and can be sanded smooth. This is really a good thing on a small boat like Friendship. The battens would have robbed her of a lot of very precious space.

There, I’m sure we’ve all had enough for tonight. Next time we’ll roll them over and pour some lead keels.

Thanks for dropping in.

Comments and questions welcome.

Paul

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



14 comments so far

View RonPeters's profile

RonPeters

708 posts in 1629 days


#1 posted 02-16-2011 07:47 AM

A picture is worth 1000 words!

Very interesting. I’ve never seen a boat being built from scratch. Much like a fiddle I’m sure?

-- “Once more unto the breach, dear friends...” Henry V - Act III, Scene I

View Greg..the Cajun Wood Artist's profile (online now)

Greg..the Cajun Wood Artist

5267 posts in 2057 days


#2 posted 02-16-2011 08:17 AM

Alot of interresting and tiedious work with excellent results!

-- Each step of every Wood Art project I design and build is considered my masterpiece… because I want the finished product to reflect the quality and creativeness of my work

View tdv's profile

tdv

1130 posts in 1819 days


#3 posted 02-16-2011 10:43 AM

Paul it’s nothing short of art, a thing of beauty thanks for sharing. By the way can you answer a couple of questions please?
1) Do you use three layers for the same reason that plywood & veneering is minimum three layers to give balance & stability to the construction?
2) On the last cladding layer presumably the planks are screwed & epoxied down, do you leave the screws in, remove them & fill the holes or replace them with brass screws?
By the way what do they call that type of stern? I used to be a trawlerman & where I live used to be one of the biggest fishing ports in the UK . Along side the big sidewinders & stern trawlers was a fleet of small (about 60 ft) wooden herring boats, we called them “Snibbys” which had that same stern design I think they were of Scandinavian origin
Best regards
Trevor

-- God created wood that we may create. Trevor East Yorkshire UK

View shipwright's profile

shipwright

5309 posts in 1546 days


#4 posted 02-16-2011 12:15 PM

Trevor, thanks for the kind words. I’ll try to answer your questions.

1) I’m not really sure if balance and stability are a factor. These details are part of the yacht designer’s realm more than mine. A boat this size and weight and given the amount of framing used needs about 3/4” thick skin. We used three x 1/4”. Some others, notably the Gougeon brothers, (the WEST System people) use more thinner pieces and may have chosen six x 1/8”.
2) The screws come out and the holes are filled with epoxy. Again in thinner skin styles the fastenings are either metal staples (removed) or plastic staples. On Friendship, with 1/8” outer layers, I used plastic staples and left them in. The top bars weren’t forced into the wood so they just sanded off when the hull was faired. Saved a ton of work.
3) Not sure. I’ve heard it called a reverse stern. I just call it a challenging stern.

If I guessed Whitby would I be close?

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

View antmjr's profile

antmjr

262 posts in 1932 days


#5 posted 02-16-2011 01:13 PM

wonderful work, Paul.
Had you to fit the planks by planing the edges? or sometimes is it possible to glue the rectangular planks without fitting them? and – more important to me – have you ever suffered from allergy? epoxy and naval varnish caused me allergic reactions some years ago, because I was so stupid to use them in a closed room, without ventilation – but I guess you too didn’t make use of protections…:-)
—-
I was wondering: is it a way to check the thickness of the hull after the final planing and sanding? (I’m thinking of the way the lute-makers build their violins, checking the thickness of the board) – maybe this question is nonsense

-- Antonio

View Maveric777's profile

Maveric777

2691 posts in 1825 days


#6 posted 02-16-2011 03:37 PM

Fascinating stuff Paul…. In my neck of the woods folks simply don’t get to see stuff like this. It is mind blowing how these beauties are put together…. Thanks for sharing!

-- Dan ~ Texarkana, Tx.

View Dennisgrosen's profile

Dennisgrosen

10850 posts in 1864 days


#7 posted 02-16-2011 04:43 PM

thank´s for sharing
those hulls have beautyfull lines

take care
Dennis

View Bluepine38's profile

Bluepine38

2954 posts in 1834 days


#8 posted 02-16-2011 04:48 PM

Wonderful tutorial on beautiful boats, I have always loved looking at wooden boats, but never realized
how much craftsmanship went into making them look so good and move easily through the water. Almost
makes me wish I was younger and lived closer to a large body of water. Thank you for sharing.

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

View Broglea's profile

Broglea

669 posts in 1839 days


#9 posted 02-16-2011 05:12 PM

Paul – How much, if any, of that 5/8” planking cracked or split? Seems like it would take a little muscle to cold bend them into place. Great blog by the way. Very interesting.

View shipwright's profile

shipwright

5309 posts in 1546 days


#10 posted 02-16-2011 06:27 PM

Antonio,
1) Because the glue being used is epoxy, an accurately band-sawn edge is just fine. You wouldn’t want gaps bigger than the odd 1/16” but the gap filling qualities of epoxies make it a perfect choice for this work.
2) Edge gluing near-square pieces without fitting them is the usual way of “strip planking” It is very labor intensive in that it requires many small fastenings to hold adjacent strips in line and it takes, even at 3/4” thickness, sixteen strips to cover a foot ! The reason it is used is that you don’t have to know how to shape planks so amateurs can get good results.
3) I admit I haven’t taken all the precautions that I should have but I knew about epoxy allergy very early on and had two firm rules: “Don’t get any on you” and “Don’t get any on the handles of your tools.” You’ll notice in the photo that I’m wearing vinyl gloves. I’ve been lucky as it’s a cumulative allergy and I worked with it for many years.
4) If you do it well there is very little wood taken off when sanding to fair the hull, so about 1/16” less than you put on should be about average. You get to check this every time you make a hole for a fitting.

Broglea, Very little. I’m sure you’re referring to what seem to be impossible bends at the stern but if you look closely at that area in the photo, you can just see that I made the pieces sort of rotate to vertical at the stern, actually past vertical. That was the only way it was about to happen. I’ll look for another photo to show this.

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

View shipwright's profile

shipwright

5309 posts in 1546 days


#11 posted 02-16-2011 06:35 PM

This is about the best I could find to show the stern planking from the inside. I hope you can see it well enough.

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

View Bearpie's profile

Bearpie

2592 posts in 1767 days


#12 posted 02-17-2011 02:42 AM

Paul, You obviously had a great passion for boat/ship building and the quality of your work shows. It may be tedious for many of us but not for those with an inherent love of building these things. It is about what rocks your boat and what may be gravy for one person is vomit to another. There are some things I do that may seem tedious to others but I enjoy doing it and get satisfaction from it! I do derive satisfaction from reading about your builds knowing that this may be the closest I will ever get to building my “dream boat” and by reading your post, I have also come to the realization that had I ever started on my boat, it would have most likely been abandoned at some point as being too much to chew! Thanks for posting and allowing us “dreamers” to wallow in our dreams!

Erwin, Jacksonville, FL

-- Erwin, Jacksonville, FL

View Napaman's profile

Napaman

5365 posts in 2826 days


#13 posted 02-17-2011 03:44 AM

incredible…

-- Matt--Proud LJ since 2007

View Schwieb's profile

Schwieb

1572 posts in 2210 days


#14 posted 02-17-2011 03:50 PM

Paul, This is simply incredible. You are far too modest. It’s been said before that wooden boat building is the height of woodworking as an art. Having admired these magnificent vessels since I was a small boy, but since building a simple by comparison strip kayak, I have an even deeper admiration for your accomplishments. I also think it’s incredible that there are people out there that appreciate this enough to pay for building these boats. These are wonderful photographs and give insight to different methods of construction I appreciate what you have done here very much and I look forward to further installments.

-- Dr. Ken, Florida - Durch harte arbeit werden Träume wahr.

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