strip planking versus clinker construction

[lvergara]

I was wondering if anybody could tell me about the practical advantages or disadvantages of strip planking versus clinker (epoxy glued lapstrake) construction for a small homebuilt sailboat? (under 20ft). I am concerned about the long term survival of a boat that would be dry sailed and kept covered on a trailer (Texas weather).

I'll appreciate your insigths. Here are a couple of pictures (taken from http://vivierboats.com/) of a strip plank built Francois Vivier's Ebihen 15 but which can be built using the two methods.

http://www.vivierboats.com/albumsen/ebihen/misainier%20strip/ebihen06_06.jpg

http://www.vivierboats.com/albumsen/ebihen/misainier%20strip/ebihen01_07.jpg

Leo

[Ian McColgin]

Epoxy glued lapstrake works best with plywood which, when sealed, is dimensionally stabile. Amazingly light construction is possible this way.

For the heft of this boat, either way is likely to work just fine, but the hull shape looks nicer strip built.

I don't understand why anyone would mess up that nice boat with an OB, much less further desicrate her bearings aft and nice wake with that well hole.

[Thorne]

Depending on the design, lapstrake would most likely be lighter and a faster build. Ian hits the nail on the head -- the main difference is the materials.

To answer the question about the boat handling hot & humid weather, if my life depended on the boat being usable 30 years from now, I'd probably go for strip built.

[boylesboats]

Strip planking with epoxy and fiberglass can be dry sailed (trailered), without any worries of leaks or separating planks.
As for lap planked, lap straked. there movements among plankings as wood swell and shrink, opening gaps to allow water to enter. No matter how good the epoxied laps, it still will open up in time while on trailer..

I would stick to strip planking with epoxy/fiberglass.. It will be less troubles down the road...
The second photo you posted, is a fine example of strip planking..

[JimConlin]

Glued lapstrake construction, using plywood planking, will tolerate life on a trailer in Texas, as will glass-sheathed strip construction. Traditional lapstrake or traditional strip construction would suffer.

If the sheathing isn't too light, the strip composite construction will be more tolerant of bumps than the lapstrake construction.

In construction time and weight, it's hard to say. It depends on your skills and the scantlings.

[Jay Greer]

One advantage of lapstrake construction is that you don't have to mess with fairing the hull much after planking.
Jay

[almeyer]

Leo,
I live just up the road from you and do most of my sailing at Offatt's Bayou, so I'm familar with the climate. My glued lapstrake Penobscot 14 stays on a trailer in the garage, and after four very active seasons, I have no complaints. I sealed the plywood with two coats of epoxy at the designers recommendation before putting on paint and varnish.
As for advantages/disadvantages, you'll probably be able to use less expensive wood for strip plank versus the relatively pricey marine ply, but you'll make up the difference in epoxy. It'll take more epoxy to fill the weave of the cloth on strip plank, whereas on the Penobscot I just painted on two thin coats.
If you're storing the boat outside, my main concern would be keeping rainwater out of the interior while still allowing adequate ventilation. That applies to either construction method. I think it boils down to personal preference; which method you feel more comfortable with. My "someday" boat - someday I'm going to build it - is about 20 foot long, and will have glued lap construction.
Al

[py]

To me strip plank is a bit too close to balsa cored fibreglass construction. To my eye glued lap ply looks more like a wooden boat. I built a 12' glued lap ply boat about 20 years ago using west epoxy. No glass. Varnished finish, using various products over the years. The transom and thwarts are celery top pine. Lives on a trailer in a shed in Adelaide where summer temps often get over 100 degrees f. Its early days yet but she's looking good so far.

[Cedric Rhyn]

John Welsford is on record as saying that the labour content difference between the likes of his Navigator and a full strip planked boat of the same general size and layout is about 2/3 in favour of the Navigator. I've seen the original Nav, on her 3rd owner after about 15 years, and you would be very hard put to find a small boat with more mileage on her. It looks like new, as much because she is well loved and consequently well maintained.

Lots of photos of Navigator and the bigger Pathfinder here.

http://www.jwboatdesigns.co.nz/index.html

Yes I know I go on about this designer, but hes relatively local to my and some of his boats are extraordinary. There are a whole bunch of several designs sail near here and the owners have the biggest smiles you have ever seen.

Ced


I was wondering if anybody could tell me about the practical advantages or disadvantages of strip planking versus clinker (epoxy glued lapstrake) construction for a small homebuilt sailboat? (under 20ft). I am concerned about the long term survival of a boat that would be dry sailed and kept covered on a trailer (Texas weather).

I'll appreciate your insigths. Here are a couple of pictures (taken from http://vivierboats.com/) of a strip plank built Francois Vivier's Ebihen 15 but which can be built using the two methods.

http://www.vivierboats.com/albumsen/ebihen/misainier%20strip/ebihen06_06.jpg

http://www.vivierboats.com/albumsen/ebihen/misainier%20strip/ebihen01_07.jpg

Leo

[openboater]

Life expecancy on a trailer probably depends more on Trailer fit and quality of the boat cover more than type of construction.

I'm working on my third stripper, a 13' Selway-fisher catboat. I like strip building because I can do it five minutes at time. and if I screw up a strip, I just cut it shorter and use it elsewhere on the hull. It is a very forgiving method of building.

[redoleary]

How big of a bad idea/difficult would it be to glass a glued lap hull?

[JimConlin]

It's easy, and often a good idea, to glass the first pair of planks before adding the second planks.
It is VERY difficult to get glass to conform to the inside and outside corners of lapstrake planking. If a glass job like that goes wrong, cleaning it up is even more difficult. I have seen very few successful efforts at glassing lapstrake hulls.

[john welsford]

If you are careful with the radius on the plank edges, and keep that to about 2.5mm which looks reasonable from a few feet away and radius the indie corner with filler you can do a nice job with Dynel run with the weave at 45 deg to the plank run. It takes a bit more resin to fill the weave but it is very good for abrasion resistance.

John W


It's easy, and often a good idea, to glass the first pair of planks before adding the second planks.
It is VERY difficult to get glass to conform to the inside and outside corners of lapstrake planking. If a glass job like that goes wrong, cleaning it up is even more difficult. I have seen very few successful efforts at glassing lapstrake hulls.

[lvergara]

I just read in the first part of an article by Paul Gartside about the building of Riff, a 12' dinghy of his design, that appeared in woodenboat 189 (March/April 2006) a comment about the advantages and disadvantages of the strip plank method.

he confirms the opinion expressed here that the method is adequate for a begginer amateur as it is forgiving and can get a high quality result. he warns though about several problems. Two points worry me the most:

1. when the hull is exposed to high temperatures, specially dark colored hulls (like the dark green shown here), the finish of the hull can be ruined at least cosmetically by the phenomenon described as "print through", which I don't know exactly what it is but I can imagine since the name is very graphic. I guess also that this may be a big problem here in texas.
2. he warns against using the method in larger boats that will live in the water beacause, no matter how the hull is sealed by the internal and external epoxy-glass fabric layers water will sooner or later manage to get inside the core, which will be a perfect incubator for rot to develop. Not that I am planning to build a large boat or keep it in the water, but I find this a particular worrisome problem.

I think I will follow the suggestions in favor of clinker - glued plywood

Here is a composite of several pictures taken from F. Vivier website (http://www.vivierboats.com) showing side by side the strip built Ebihen15 and a clinker version (different rigs, but that's another story)

http://im1.shutterfly.com/procserv/47b8df39b3127cceb3a727384cc400000026100AZMmbRi2bt2 Kg

I have not selected my dream boat yet, I am still looking. But I like a lot this large dark green hull... the clinker version is not bad either

Mr Vivier sent me a drawing of the new Ebihen16, an elongated version of the boat shown above, with the same width, but incorporating water ballast...

A boat like this would be probably an ambitious project, so in a more practical and realistic mindset, I am also considering boats in the sail an oar class, one candidate is the well known "Ness Yawl", but I also like a lot the "Youkou Lili" (described as a cross between the flat-bottom American Swamscott Dory and the double ended Norwegian Faerings), here are some pictures from the same website (no strip plank option here):

http://im1.shutterfly.com/procserv/47b8df39b3127cceb3a727264cda00000026100AZMmbRi2bt2 Kg

Thanks for the comments, have a great weekend!

Leo

[RodB]

Boy, some real pretty little boats there.

Its fairly obvious that you could build with either method and end up with a fine boat that would certainly stand up well. Since strength would not be a problem with either method, I would think aesthetics would be the deciding factor (smooth hull or not) contrasted with the amount of labor required and desired hull weight. I also think the pics above at the beginning of this thread show a really sweet strip-planked hull that would not be the same in glue ply lap construction... just my personal opinion. Keep this in mind, any boat that will be trailered and kept covered will do well over time with a little commonsense scrutiny. Also one designer/builder once said to me...if you kept a coffee table (with just about any finish on it) in your garage out of the elements, it would keep many years almost as good as new....with no maintenance.

The canoe yawl "Wenda" in the following thread was built glued ply lap and...and at over 25' and 4000+ # displacement... lives on a trailer and has been fine for many years. The builder used Sapele ply and made absolutely sure all end grain was sealed very well. I think he glued strips of hard wood on the edges of the lapstrakes in addition to sheathing the exterior. This builder says he thinks of the lap joints as small stringers running the entire length of the hull resulting in lots of stiffness. He's a strong advocate of glued ply lap hulls and always points how how strong and stiff and light you can make a hull with this method.

http://www.woodenboatvb.com/vbulletin/upload/showthread.php?t=2249&highlight=Albert+Strange%27s+Wenda

On the other hand, the following schooner is built strip/cold molded and this guy will be keeping her in the water all year long. Since this hull is over 28 feet LOD and a heavy displacement design, he wanted a bullet proof hull...so he added two exterior layers of veneer to stabilize the hull, in addition to xynole fabric for exterior sheathing. The interior surface between the frames was also glassed.

http://www.woodenboatvb.com/vbulletin/upload/showthread.php?t=70274

A few years ago Tom MacNaughton and Paul Gartside had a very detailed debate on the MacNaughton website forum I think... where they argued the pros and cons of sheathed-strip boat building. I do not think Mr. Gartsides is the final authority here by any means.... perhaps this is a controversial issue but there are many sheath-stripped hulls standing up fine over the years on trailers and in the water all year long. Its all about proper construction with proper materials. For example, if the exterior of say a 30 foot sheathed-strip hull is sheathed with two layers of 10 oz fiberglass cloth...thats a pretty good moisture barrier when you throw in a few coats of epoxy primer and then bottom paint.

MacNaughton's "Scantling Rules for Sheathed Strip Construction" may be of interest to you. . . as this method should allow you to build the strongtest hull at the lightest weight. The sheathing with fiberglass cloth both inside and outside the hull is a structural element and must be done properly to result in a proper hull. I discussed this issue at length with both Mr Gartside and Mr MacNaughton and was able to get a very clear idea of what each gentleman was saying. It was very interesting...and folks must make up their own minds. Also, comparing glue ply lap to sheathed strip construction... I wonder as you approach the thickness of the ply for sheathed-strip building, if the two methods probably come close to the same weight.... or at what parameters they are similar in weight. Also, the smaller the design you decided to build, it seems it would be easier to use thinner plywood to go lighter...over building strip-planked. I guess you have to take into consideration that ply is a little heavier that solid wood because of the glue lines...in the same thickness. I would not be worried in the least about the concerns you raised if building a boat sheathed-strip construction...and storing on a trailer.

FYI, "print thru" is minute creep between the joints...by epoxy before it reaches its endgame totally inert state...and the joints between the strips show up very slightly...because the human eye can discern two to three thousandths of an inch differential height. Per Tom Macnaughton, this happens sometimes with professionally built hulls because the hull is built quickly, relatively speaking, so the epoxy can suffer from minute creep if heat is added like the sun on a dark hull. With amatuer builders, they usually take so long to build a hull, that the epoxy is as stable as its ever going to get by the time the hull is done. Tom also said that if this print thru happens it is easily taken care of with the first hull topsides repainting. Just a little sanding prior to that paint job removes the print thru and that pretty much takes care of it.


Good luck

RB

[keyhavenpotterer]

Perhaps Vivier has just offered another alternative. His Meaban can be built with ply plank and ply cold moulded sides. See here

http://www.vivierboats.com/albumsen/meaban/construction_CP/index_en.html

[lvergara]

Dear RB

Thanks for your response, this thread has been very useful for me. I need to make an small clarification about my interpretation fo Mr Gartside's article: I strongly apologize, I think I did a very poor job summarizing Mr Gartside's writing, this is what happens when an ignorant in these matters like me, tries to sinthetize in two lines a whole page written by an experienced designer. I think in the article Mr Gartside completely agrees with you in the use of strip plank-cold molding combination for larger boats. I was extracting from the general context only what I understood about the use of strip planking alone...



Leo

[RodB]

I was referring to as you say "strip planking alone"...which is properly referred to as "sheathed-strip construction". Sheathed strip construction is strip-planking with fiberglass sheathing on both the inside and outside surfaces... no cold molded veneers. Perhaps I should not have used the strip/cold molded example. The concerns you mentioned are what I was addressing and I am confident that you would not have any worries with "strip planking alone".... ie., sheathed-strip construction. Check MacNaughton's websight and read about their scantling rules etc.
http://www.macnaughtongroup.com/default.htm
http://www.macnaughtongroup.com/scantlinsheathed.htm

http://www.macnaughtongroup.com/publishingown.htm

I'mnot sure building the Meaban with ply sides cold moldind would save a lot of time and be easier...to just plain glued ply lap...??

RB