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Feb 07, 2017, 04:48 PM
Classic wooden RC sailboater
SeattleRCSailor's Avatar

Vintage Marblehead Resurrections

Hi everyone,

I've been captivated lately by doing some 3D modeling of two Vintage Marblehead sailboats from the 1940's. My thought, although I'm not sure how far I will be able to pursue it, is to resurrect these two boats and make the lines and files available to builders out there. My goal is to update the boats to incorporate a more modern keel attachment using modern plywood and epoxy. The build will also be moderized by using laser cut frames and a plywood keel system. No, it probably won't be any lighter, but will certainly be sturdy, and the boat should last for many years of enjoyment.

So far, I've pretty much completed my take on the Sun Wind. I call it the Sun Wind II because I'm sure that I made enough changes to the hull, fin and rudder to merit the "II". Yet, in studying the VM rules, I am convinced that this "new" Sun Wind will be class legal for anyone wishing to race it. I'm not into racing, and this boat will probably not be light enough to be very competitive, but we'll have to wait and see how much it weighs when done.

All I had to go by were an old, but pretty, set of lines that were taken off of the original boat many years ago. Here are the original Sun Wind (apparently originally called the "Sun Daze") lines that I used:

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From that I have modeled the entire boat, and hope to laser cut the frames for it shortly. I dropped the keel down to a 16" draft, and added a spade rudder, both legal under the VM rules. Here's how it looks in Sketchup Pro so far.

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Description: The updated lines for the Sun Wind II created by me in Sketchup Pro. Name: All frames image.JPG
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Just starting on modeling the Rip Tide as well. I was given a beautiful hull by Rod Carr to finish, that some gentleman had started years ago. That same gentleman also did some CAD work on it, and I'm trying to model the boat based on his CAD lines. He seemed to do a nice job, although he clearly meant to draw it in 2D, as many of the lines aren't connected to make 3D surfaces and solids. It's taken a lot of work to get into 3D so far, but hopefully I'll have something to show in the near future.

If interested in knowing more, or seeing more pictures of what I have done so far, see my RC Sailboats Blog.

Thanks for any comments!

Last edited by SeattleRCSailor; Oct 23, 2017 at 07:11 PM. Reason: More inclusive of all VM boats
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Feb 08, 2017, 06:21 AM
Registered User
You have my attention, love the VM and hope to build one soon

Thanks Steve,

Feb 08, 2017, 06:38 AM
Thomas MM GER15's Avatar
Hi Steve,

nice project!

As well the unfinished build Riptide you got from Rod Carr!

May I ask why you do not design a removeable keel? Or at least in terms of better stability a fin attachment into the hull structure similar to that. These old boat have plenty of lead at the bottom and to glue the fin only into the lower bottom of the hull structure looks not well designed to me.

Feb 08, 2017, 06:57 AM
Classic wooden RC sailboater
SeattleRCSailor's Avatar
Hi Thomas,

So this is my big experiment. The keel in that area has three laminations of plywood, plus underneath the hull I will filet in the garboard hollow with thickened epoxy. My hope was to keep the interior open. I'm making up a test hull soon and this is my biggest question.

If it doesn't work then I will have to adjust and probably do something along the lines of your suggestion by extending the inner core of the fin up so that it connects with frame 4. That, or make some sort of additional box reinforcement structure perpendicular to the keel. It's all for fun, right?!

As soon as can get to the laser cutter at work, I will then get testing!


Feb 08, 2017, 07:20 AM
Thomas MM GER15's Avatar
Hi Steve,

Ok. If you build it strong it will be ok for sailing, there have been several old Marblehead boats with fin attached just to the hull bottom up to the early 80ties. But to get the required stiffness and durability you have spent relative much material thus also weight. Even in an oldtimer which has plenty of displacement I would try to avoid such construction as well as today we know about better structural constructions.

Btw. I am happy to own an oldie marblehead as well, but a little younger one than these two boats. Its from end 70ties:

and was sailed / raced many years in European events by it previous owner.

The keel attachment of this boat is also of unusual construction, but the designer and builder made several boats in same way up to 10R. As far as known all without problems (just in case of a replacement it will be a hard to build such a keel new and the designer died already many years agoÖ)

I also remember of well known and successful european Marbleheads in early 80ties where their removeable fins were attached to the more or less reinforced buttom of the hulls just by two bolts! Very similar to big boats keel attachment - but why? The fin top was somewhat wider designed as well, but all in all the forces where handled just by the stability of the laminated hull shell. I never liked that as it is not required to have inside a hull such free room on RC yachts. Even you would add several remote controlled trim functions there is always plenty enough room for that around a fin box, which also gives additional stiffness to the hull structure.

Feb 08, 2017, 10:20 AM
Classic wooden RC sailboater
SeattleRCSailor's Avatar
Part of my thinking is related to the Star 45's I've built. They have removable fins that are held in place by two bolts that run through the entire hull and screw in on the deck. Some make it so that they screw in just below the deck.

Those fins, with similar weighs in the bulb, are held vertical to the hull by only two stainless steel threaded rods at the hull/fin joint. There is not garboard buildup, and no filet of thickened epoxy. They work very well. So my idea is that this fin, with a much larger fore-and-aft length, and epoxied to the keel, and then with thickened epoxy on the outside, MIGHT just be enough to hold it sufficiently. It certainly won't break free and fall off the boat, but it could crack the hull (and sink the boat!). My frames 5 & 6 are doubled 1/8" ply (for 1/4" total in each frame) and are tied (slotted and epoxied) to the keel.

But it's all a big experiment and I'll do some stress testing to see how well it holds up. By "stress testing", I mean that I'll try to bend the hell out of it, and I'll also be stressed about it until I know for sure!

Feb 08, 2017, 10:37 AM
Registered User
You might want to take a look at the micro magic keel shim system. In use it seems to be set once for the strength of the prevailing winds but that might provide some ideas.

Is the deck flat? It or real easy to set the deck as flat (not the waterline) which makes the mast and rudder stick out weird.
Feb 08, 2017, 11:02 AM
Classic wooden RC sailboater
SeattleRCSailor's Avatar
The Sun Wind deck is flat fore-and-aft, and has a slight crown running amidships. I've also got a mast support running down to the keel on frame 4 which is underneath the mast.
Feb 11, 2017, 10:34 PM
Classic wooden RC sailboater
SeattleRCSailor's Avatar
Last week I spent some time on the laser cutter, and cut the first sheet of 9 sheets for the new Sun Wind II Vintage Marblehead. Then I went back to the computer, and after several tweaks, changes, and adjustments in Sketchup Pro, I now think I'm ready to do a full-blown laser run of all 9 sheets.

Here's how the sheets look as of now:

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I also learned a lot after my first trial run on the laser cutter, and then came home and completely reworked the servo board. Here's how it looked after the first run:

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And here's how the reworked version will look:

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More later when I get back to the laser cutter. If you'd like more pictures or updates, visit my blog.

Feb 12, 2017, 01:06 AM
Registered User
The circles may look cool but they are not really time efficient for removing material (lite-aning) you might have better luck with triangles and a "filleting" tool to "radius" corners to both deal with stress and reduce the amount of area you need to keep water proof. The particular design you used is the very special "I want to lose any dropped nut or bolt" motif.

That laser is really good for marking to so why not toss some numbers on the parts? It's not difficult to figure where things go but having 9 and 9.1a in your hand makes it a lot easier to track revisions. If you want to be really tricky you can mark lines to aid in planking. You can run a bunch a rectangles on a laser printer to make planks if you can find thin enough wood and the stage is long enough.

If you are using dimensional lumber (sticks and dowels) there should be wood to support the mast, eyelets, and fairleads. How can you use a slightly heavier stick to transfer a load so you can use a lighter deck?

I really like an open transom for some reason as it is a detail that kinda looks like a real boat.

Looks like the removable keel is not included. Looking forward to the next pass to get ideas for my boat. Are you building a provision to move the battery pack fore/aft? It helps if you have light wind almost always but want to try a windier day.
Feb 12, 2017, 10:24 AM
Classic wooden RC sailboater
SeattleRCSailor's Avatar
Hi Pwallace,

Ha! Yes, I agree that the servo deck is perfect for losing nuts and bolts. The holes are not for lightening the board but instead are purely aesthetic. Those who know me, know that I am 70% about aesthetics, 28% about strength, and 2% about racing. This boat will look cool, if perhaps a bit funky, and will be very strong.

Is it the best setup for racing? Nope. But it will be a fun, strong, nice looking boat that should last for years.

Wait until you see my swing arm and booms. THEY are funky. :-P

Regarding your comment about being time-efficient, we have a 90 watt laser that cuts fairly quickly so it's not really an issue. Those holes took seconds to cut. Besides, I'm not in a rush. It's the designing and making of it that's fun.

Regarding your comment about labeling the parts. I agree 100%. You can't really see it in the image I posted, but most of the parts are labeled with the name and number, and when appropriate, the side.

For the lumber though, I will mill my own. I'm fortunate enough to have a very nice table saw and other tools. This way I can get the wood I need in the species I want. I would not cut the decking or planking from the laser unless it was really necessary. The laser, while being very cool and fun to work with, gives a recognizable cut and appearance. My own milled wood retains more of a custom look. Much more craftsmanship-like. I'm all about using all the tools I need, but only when they are appropriate and add to the overall finished product. Again, I'm really into the aesthetics. All that said, I could potentially see, for a cheaper but quicker build, to have a plywood deck that has the "planking" scored into it with the laser. I've seen some and they look OK, although almost too perfect really.

I too like an open transom, which is why I made one on my Salish 475. However, the Sun Wind II is a Vintage Marblehead boat and must, according to the rules, remain with the overall design of the day (1940's - '60's).
Feb 13, 2017, 10:12 PM
Registered User
Originally Posted by SeattleRCSailor
... It certainly won't break free and fall off the boat, but it could crack the hull (and sink the boat!). My frames 5 & 6 are doubled 1/8" ply (for 1/4" total in each frame) and are tied (slotted and epoxied) to the keel. ...
Steve my Mystery Boat was built this way sometime back in the 80's (our best guess) and it held up I guess long enough to make it to now. When I got the boat though it was, is in sad shape. As I was trying to fix damages done to the hull over the years from it flexing, a small crack around the fin turned into a long hole.

A lot of time went into trying to figure out a solution. But the best solution is probably to prevent the issue from the start. That hull is basically junk and now just holding up sails and a mast that aren't worth much more than the hull.

Your solution sounds a lot better than the way this boat was built though. Maybe it will hold up okay...
Feb 14, 2017, 07:48 PM
Classic wooden RC sailboater
SeattleRCSailor's Avatar
Got the first round of frames and parts cut today on the laser cutter. Now I'm mocking them up to find any changes and tweaks. So far it's working pretty well, but I've found a few things that need correcting. Overall though, I'm very happy so far!

This round is intended to only be a mock-up. I will use it to gauge how well the frames are faired to each other. It will only be a skeleton when done, and will be on display at my school (I'm a teacher) in the maker shop we have.

Then, when it's all tweaked and faired, then I'll make a final cut and build the actual boat!

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Feb 14, 2017, 09:01 PM
Onward and Upward
CatManDu's Avatar
Cool Beans. I like the idea of restoring older boat designs with modern updates. Good job.
Feb 17, 2017, 01:00 PM
Classic wooden RC sailboater
SeattleRCSailor's Avatar
An update on my Ďmock upí version of the new Sun Wind II RC sailboat. Remember that this current build will not become a complete boat, but rather is being done to test for fairness and other things. It will eventually be half planked and then put on display at my school (Iím a teacher).

This is a picture of the fin to frame connection. This, again, is my big experiment with this project. The fin is one layer of 1/8" ply, and then 6 layers of 1/16" ply, for a total of 1/2". The layers are then tied into a series of three doubled-up 1/8" frames, for a total of three 1/4" laminated frames. Where they meet, they slot into each other with a total overlap of about 2". You can also see an empty slot for a half-frame that will be added shortly. They are epoxied together, and so far, even though obviously still on the building board, seem as strong as steel!

If I want, I could add some 1/4" x1/4" or thicker stock to each of the corners to build up the material. I don't think I need to do that though. At this point, Iím pretty convinced that this will take the stress. We'll see!

You can also see the rubber band system that I use to clamp the stringers and sheer rails. Works very well. Can be adjusted to use with planking too.

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Last edited by SeattleRCSailor; Feb 17, 2017 at 08:41 PM.

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