So, trailered classic runabouts

[Roger Stouff]

I see a lot of them on trailers, particularly at the boat show held in Madisonville, La. in the fall.

These classic Chris-Crafts and the like, I thought they needed to stay wet with plank construction? How to they live on trailers so much without drying out and separating or splitting? And if one were to build a traditionally planked runabout, how would one keep it intact if it will live on a trailer for weekend/occasional use?

And pardon my lack of knowledge, but are these boats "plank-on-frame" or "batten seam" or what's the correct terminology?

Just wondering... :cool:

RS

[Jack Heinlen]

Roger,

Musings, I'm no expert.

Last question first. Batten-seam is one of three main methods of plank on frame construction, the other two being lapstrake and carvel. Definitions have become kinda fuzzy, but solid planking fastened to the frame with mechanical fasteners is what it means to me.

The bottoms of the 'classic' runabouts were ususally double-planked, with a layer of cotton cloth and varnish or shellac between. They were often used as day boats, and stored in hoists or boat houses when not out running about, and the method worked pretty well. Some were also kept in the water.

Restorers, for the most part, have turned to cold molding new bottoms. This makes a restored boat able to live on a trailer quite nicely. I don't know the details of precisely how they do this now, but when I was active and looking at such things they rebuilt the basically same double-planked configuration of the original, and glued the bejesus out of it.

Maybe that will get the ball rolling. If D. Dannenberg were still lurking he'd come in and set us straight. He, by the way, is an interesting restorer who would be worth contacting about such questions. From the look of how busy his shop is(someone posted a link recently, and he's going great guns from the look of things), it may be hard to get ahold of him.

Best of luck Roger. Is there a candidate you have an eye on?

Jack

[ 07-26-2004, 06:54 PM: Message edited by: Jack Heinlen ]

[Roger Stouff]

Howdy, Jack...

Yes, I'm interviewing candidates for my next project. I'm going to do that runabout, inboard powered. The more I consider cold-molded, the more I don't know if I am getting farther away from what I love about wooden boats. My first three boats have been sheet plywood, and I'm wondering if maybe I need to take a step the other way now.

It's all study and think, right now. I may end up right back where I started from, with a cold-molded new design. Or I'm looking hard at Edwin Monk's "Tern", a 1930s era 18' runabout planked in 1/2 inch mahogany. Thus this question. I am unclear on how trailered boats do not separate at the seams, or if they do, and from my readings through the archive, unclear about the use of epoxy to stabilize them to prevent it. I don't think I want to deal with caulked seams. Anyway, I'm seeing valuable MMD's advice on that particular design also.

Thanks for your input. The advantage, in addition to your valuable experience, with living up north is a familarity with these boats, which we here in the deep South do not have much of.

Best,
R

[ 07-26-2004, 07:28 PM: Message edited by: Roger Stouff ]

[Jack Heinlen]

Hm.

I think I'd bite the bullet and use the epoxy double planking on the bottom(or what is accepted and good practice today), and then build the boat like it was built in the thirties from the chine up.

Mucking with epoxy is a nasty business.

Spiling, fairing, and fastening planks of mahogany is sweet. The deck structure, the seating, all of that is pleasant work without the glue, but it makes sense to modernize the bottom, I think.

Building it completely to plan makes more sense, aesthetically, from a working point of view, than building cold molded.

Batten seam topsides would work fine with trailering. And no caulking.

You'd end up with a hybrid, which is what most restorations are.

[Roger Stouff]

Sounds about right. I've had the experience of mucking with epoxy, it's nasty, but necessary in my kind of applications, I'm afraid.

[Don Z.]

Roger,
This is difficult for me to explain without some good pictures, but try and stay with me and I'll do the best I can...

Let's start with lapstrake... just because we all are pretty clear on that. First the molds go on..,. then the planks are bent overlapping each other, then the molds get pulled as the frames are steamed in... many variations, but that's just the basic, OK? For all others who want to pick nits... I know... but I'm trying to keep it simple so it's clear.

Now compare that to carvel. First we do the molds... then wrap battens around them. The frames are steamed to the battens, and then the battens are removed as the planks go on. Because the word carvel has more than one syllable, it is "shortened" to "plank on frame" in some dialects.

Now, as you've pointed out, the lapstrake does not have some of the caulking/shrinking issues, because the planks overlap. There is some shrinkage, but as long as you have enough overlap, it stays "watertight". However, the overlapping doesn't give you smooth sides, and it's really limited to certain types of shapes. Carvel will give you those smooth sides... But you clearly understand how all the shrinking will pull the planks from the caulking.

So what if we did this... The runabout shape is fairly well suited to sawn frames. instead of laying the battens ON the molds like you did for carvel, these sawn molds will BE your frames. The battens are not layed on, they are "notched in". The battens should also be a bit wider (sided, not molded) than you'd use for plank on frame. Take some time with this, because they will be very important later. When you lay your first plank, don't just spile it to the garboard seam and let it end where it may... spile it in to the garboard seam, and then spile the other end to meet the CENTER of the first batten. It's "wider" than plank on frame, because you want both that plank to rest ON the batten over its entire length, and you want the next plank to lay on the batten as well... In short, the planks are laying atop the battens... they "overlap" here, and so can stand a little shrinking and drying. The fastenings will go into the mold/frame, but the planks will be backed along their entire length...

I hope that explains it... as I said, with a picture I could make it very clear, but I don't have pictures of the construction readily availible (though I think Chappelle's Boatbuilding has some good sketches...

Having said all that... if it were me... there is a "best of both worlds". Ply would lay on the typical runabout bottom very well... and you could batten seam the topsides and deck. You'd be minimizing your epoxy use, have a light, strong, watertight bottom... and still be near where you want to be with this boatbuilding thing. On the other hand, if you went batten seam, you'd have some of the problems mentioned (the batten seams aren't completely watertight, hence the double planking)... and I'd still use epoxy/dynel vice shellac and canvass... but it can be done.

[Roger Stouff]

Yes, I do understand. And I think that's the way to go.

I'm scanning the Monk designs from the book tomorrow (hopefully!) to confer with Michael on some particulars on power plant, etc. I'll post a few here.

Given the options, I like these ideas better than cold-molded.

I love this hobby! smile.gif

You've all been most kind...

R

[Ross M]

I have thought about this a bit and read about it a lot, and would like to make a few points:

a) Do not commit to anything until you have read Don Danenberg’s “How to Restore Your Wooden Runabout” (formerly “Runabout Woodworking”). The section on steam bending kiln-dried lumber is worth the price; the information about building a long-life trailered runabout is icing on the cake.

b) If you begin to doubt Dan’s allegiance to 5200, review the writings of the Chemist with regard to adhesives. (I could sum them up for you instead: Extremely stiff and strong adhesives are a great way to inadvertently expose fresh wood to the elements).

c) Tern is a beautiful design, but she suffers a common failing: The batten-seam bottom. B-S seems acceptable for topsides but has achieved a reputation for poor longevity in bottoms. Same with carvel inner layers in multi-layer bottoms. Blame gravity, I guess. Praise the gods for plywood.

d) If you can work around the above, there is a V8 package that might meet the 350 lb requirement – the early 60’s Graymarine Fireball 160. It was based on the Buick 215 CID aluminum engine shown here: Buick 215 V8 (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33615&item=7909386921&rd=1)

Ross

[rustnrot]

Option 3: http://www.imagestation.com/album/?id=4286100427

the pics show a fiberglass inner hull. I have a Gar Wood Speedster mold (off an original) and make fiberglass hulls that you glue the mahogany on the outside from the waterline up. The twin cockpit shown is off the same hull. And the rotary engine weighs 377 lbs. with the tranny, 175 hp.

[ 07-28-2004, 07:01 PM: Message edited by: rustnrot ]

[Roger Stouff]

Rustnot, what is it?

Ross, agreed in full. I've never used 5200, so that's no issue. smile.gif

[JimD]

Roger, I like what Don Z has to say. But I wonder if something like glued batten seam would really look all that much better for the extra work it would be. You already have built a Glen-L Zip, yes? So you know how sharp a plywood hull can look if you take the time and care to finish her bright. Even my little bright finished meranti Utility looks sweet. There was a thread a few months back about the pros and cons of going to the trouble of cold molding or double planking a convex curved bottom and apart from making for a slightly dryer ride it hardly seemed worth it to me. I've also thought about glued lap plywood, possibly with battens for added strength, to look something like an old lapstrake Lymann (sp) but I get off topic...

[Roger Stouff]

Jim,
I agree completely, but find me a set of plans for a sheet-ply runabout in 18-20' and I'll send you my firstborn child. smile.gif

Actually I have only found one, Glen-L's "Mist Miss," and her lines are dreadful to my eyes. Other than that, I have found a 17-foot on Svenson's free plans page which might suit me, it's called "Riviera." Might need some tweaking, but I'm getting closer.

Thanks,
R

[htom]

There are a couple of others, too, on the runabouts page, marked with the circled plus:
http://www.boat-links.com/Atkinco/Utilities/ShoalsRunner.html

(Although she'd probably not be appropriate for that big V-8!)

[Jim H]

Originally posted by Roger Stouff:
Jim,
I agree completely, but find me a set of plans for a sheet-ply runabout in 18-20' and I'll send you my firstborn child. smile.gif
18' Plywood Runabout, Downeaster (http://www.woodenboatstore.com/store/prodinfo.asp?number=400-071&variation=&aitem=4&mitem=19)
http://www.woodenboatstore.com/store/images/400071.JPG

19'7" Runabout (http://www.woodenboatstore.com/store/prodinfo.asp?number=400-136&variation=&aitem=18&mitem=19)
http://www.woodenboatstore.com/store/images/400136.JPG

This last one is Strip planked over sawn frames. IIRC, Doug Hylan built a Bermuda runabout that was featured in one of the WB issues a couple of years ago, again not plywood but a nice runabout.

Edited to add: Gee, all I had to do was read a little closer:Built by eye in the Bahamas for the last 40 years, Doug Hylan's drawings allow for strip-planking or cold-molding.

See WoodenBoat Issue #135 for an article about the Albury Runabout.

[ 07-27-2004, 04:25 PM: Message edited by: Jim H ]

[Roger Stouff]

redface.gif Okay, let me rephrase: Sheet ply plans for...

http://www.boatdesigns.com/store/Html/Products/images/barrelbk.jpg

Sorry, but thanks for trying! smile.gif

[Jim H]

Whoops! When people say runabout the Lyman type runabout is what comes to mind. The best I could do for the type your thinking of is a handful of cold-molded designs.

Clark Craft - Runabouts (http://www.clarkcraft.com/cgi-local/shop.pl?type=categ&categ=017&cart_id=)

[htom]

http://www.glen-l.com/designs/inboard/skiking.html ? (stretches to 16.5')

http://www.selway-fisher.com/McClassic.htm#TARANTO ?

[ 07-27-2004, 05:30 PM: Message edited by: htom ]

[Bob Perkins]

Roger,

I'm building a mahogany runabout *replica* that is cold molded. It is a Ken Hankinson Design. Hankinson (http://www.boatdesigns.com)

You can go cold molded (like Mine) or get Nelson Zimmer plans and build one like they did in the 40's. (Batten seam)

Don Dannenbergs book explains how he does traditional bottoms, but using 5200 instead of canvas. He has some out there well over 10 years old. This bottom has flexibility and stability. The original canvas sandwich bottom wore out/dried out. If you were to use an plywood/epoxy/planked sandwich bottom - you may have problems. Don's book outlines them.

The original mahogany runabouts (Chris Craft et el) Were build assembly line style - much like cars. They were also expeced to live the life of a car - 10 years or so... They were not really designed to live 50 years.. hence restorers...
Don's restoration program and new bottom technology was interesting reading.

It doesn't apply to double diagonal strip planked construction like the boat I'm building though.

-------------
Regards,
Bob Perkins

My out of date site is at:
http://robert.perkins.home.comcast.net/

My Current project is at:
http://www.imagestation.com/album/?id=4291051329
-------------

[Wayne Jeffers]

Roger,

Looking at the plans for Tern, she is shown planked with the "batten seam" method. Note that on the inside of each seam in the half-inch plank is a 3/8 X 1 1/2-inch batten. Monk describes the method on pages 14-15 of his book, "How to Build Wooden Boats", available from the WoodenBoat Store. The plank edges are fastened to the battens at close intervals. Seams are caulked with cotton and putty (less than ideal if you want a bright finish.) Monk refers to caulking from the inside for a bright finish; this sounds complicated.

It looks to me like it would be easy to plank the bottom in plywood, since there are no curves and the twist doesn't look too severe. If necessary, you could plank with two layers of quarter-inch ply instead of a single half-inch layer.

Since the seam battens would add strength, I would plank the bottom with three layers of quarter-inch plywood if battens were omitted.

If you plan on using an engine of more than the 15 to 40 HP shown in the plans, the bottom will probably take more of a pounding. Maybe a good idea to retain the "battens" as stringers for strength and maybe increase the scantlings on the bottom planking, too. Best revised scantlings due to increased HP would be a good question to throw at a marine engineer. ;)

With the state of the art today, I expect cold molding would be the most practical way to achieve a bright-finished topside with little maintenance beyond periodic re-varnishing.

Wayne

[Jon Etheredge]

Several people have suggested that you should be able to plank the bottom of Tern with plywood. I'll come in on the other side of this and say that I doubt you will be able to plank this boat (as it is drawn) with plywood.

Even if you go with multiple layers of thinner plywood on the bottom, the sheet goods will have to be tortured pretty significantly to get it laid. In the process, you will introduce buckles and the bottom will probably not come out very fair.

You could modify the design so the shape of the bottom is a developable surface (or is at least closer to developable)and then you will be able to use sheets of plywood. More than likely, you will end up changing the shape of the stem/forefoot some and the sections will have some convex curvature as you approach the bow. The stern will probably remain basically the same.

The topsides of this boat show a concave curve in the first couple of sections. I don't think you will get sheet goods tortured into this shape.

If you want to retain the shape of this boat with modern materials and techniques, I think you'll have to cold mold. You could always use ply for the cold molding as Ken Bassett shows for his Rascal.