Roman´s OB15 (First Time Builder)

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RomanVilgut
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Roman´s OB15 (First Time Builder)

Post by RomanVilgut » Mon Aug 12, 2019 7:32 am

Hello,

at first I want to thank Ruben and Jacques for the Answers to my Questions in

viewtopic.php?f=2&t=64292&p=452326&hilit=ob15#p452326
and
viewtopic.php?f=12&t=63695&start=170

It´s getting serious. Since I live in the city (Graz) i am working in the barn of my father in Law. I thought it would be big enough, but it´s getting tight...

Build the jig and molds. After cutting the molds I realized, I forgot the camper. So I used some of the wood, to "make" cambers. I hope, this will work...

Also did some cutting already. I have two weeks vacation in September, where I want to make as much progress as possible - with the help of my wife. I want to finish all the pre-work before September, e.g. cutting and glueing the pannels. Should I cut all parts before I start, or should I cut them, when I need them?
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Jig_Molds.jpg



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glossieblack
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Re: Roman´s OB15 (First Time Builder)

Post by glossieblack » Mon Aug 12, 2019 8:20 am

Welcome Roman! :D

I am not familiar with the build plans for the OB15, but I strongly suspect that you build the hull as wide joining curving planes first, epoxy then glass tape them together, then glue on' what you're calling 'camper' or 'camber' external strips (strakes) latter.

Others with more knowledge of the OB15 design will no doubt chime in.

Enjoy your build - I'm looking forward to following it. :D
Completed R13 two part nesting rowboat. ST 21 under construction .... where seeking perfection is recognized as the enemy of the good.

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Re: Roman´s OB15 (First Time Builder)

Post by Rtorres2411 » Mon Aug 12, 2019 9:08 am

Hello Roman
It’s nice to see you have started the OB. The jig and mold looks good, but be careful with the pieces you used in the molds for the lack of camber. Since you don’t have a complete camber those pieces of wood could create hard spots and prevent a nice fair hull bottom.
Don’t cut your bulkheads yet, wait until you flip the hull and measure the hull where the bulkhead goes. I used cardboard to make bulkhead half sections, then transfer the measurements to the wood.

Happy building
Ruben

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Re: Roman´s OB15 (First Time Builder)

Post by jacquesmm » Mon Aug 12, 2019 10:18 am

Don't worry too much about that camber, you can build without it.
The idea is that when bending the plywood close to the bow, the ply will assume a conical shape.
That works well with Okume plywood, not so much with stiffer ply. In all cases, do not worry if the plywood does not fit perfectly to the molds close to the bow. Let it take a natural shape. Try for fairness first.
Your jig looks good, keep posting please.
Jacques Mertens - Designer
http://bateau.com

RomanVilgut
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Re: Roman´s OB15 (First Time Builder)

Post by RomanVilgut » Tue Aug 13, 2019 3:04 am

Thanks! I will remove the camber and see what shape the plywood will take. Next step for me is glueing the transom and the side panel. My first time with epoxy... I will make a testrun on some of the wood that is left over from cutting...

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Re: Roman´s OB15 (First Time Builder)

Post by RomanVilgut » Mon Aug 26, 2019 3:35 am

Yesterday I made the bottom. I am using cotton and fiber as putty filler. Works out good for me.

I think i am going to lower the jig about 10 centimeters (4 inch). I am 1,8 meters (6 feet) tall and really had to stretch, to epoxy the keel.

Wanted to do the side too, but when i was cutting the panels, I was a little stubborn and wanted to do all on one day without a break. The result: I somehow made an error with the side panel, lost five centimeters (2 inch). So I had to order a new plate. It will be delivered next week. So my tip to myself and all builders: Make breaks and simply stop working, when you lose concentration...

I also developed a tennis elbow, so I am going to make a little break (2 weeks) from building.
ob15_bottompannel.jpg
But I am very happy with my progress. One Question though. I use clamps to hold the panels in place, but I will have to remove them, when I do the side. Can i use zip tie to connect the panels to the jig? And when should I remove the zip ties at the keel?

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Re: Roman´s OB15 (First Time Builder)

Post by joe2700 » Mon Aug 26, 2019 3:44 pm

RomanVilgut wrote:
Mon Aug 26, 2019 3:35 am
One Question though. I use clamps to hold the panels in place, but I will have to remove them, when I do the side. Can i use zip tie to connect the panels to the jig? And when should I remove the zip ties at the keel?
Once you attach the side panels to the bottom with zip ties the weight of the side panels will do a lot of the work to hold the bottom against the frames. Where it doesn't you can use temporary screws to pull a panel in to the frame. Just don't make them very tight or you get a flat spot, just enough to pull the panel lightly against the frame.

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Re: Roman´s OB15 (First Time Builder)

Post by RomanVilgut » Tue Aug 27, 2019 3:43 am

Thanks, never though about temporary screws. But I really think, this will help.

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Re: Roman´s OB15 (First Time Builder)

Post by RomanVilgut » Fri Sep 20, 2019 7:07 am

I spent some time of my vacation for the boat and made some Progress. After cutting and glueing the side-panels i could strap them to the molds. I did not need screws for the bottom pannels, after two weeks with screw clamps, the pannel was nicely fitting in place. I straped it to the molds with zip-ties.
1909_boot5.jpg
1909_boot6.jpg
I then did the chine with epoxi and used cotton and fiber as filament. With the help of my wife, I could get the nicely flat, using an dough scraper.
1909_boot4.jpg
After that, i did the sanding and applied the fiberglass-tap (10cm). That did go ... let´s say, ok for a beginner
1909_boot1.jpg
I really tried to have no bubbles, using rolls instead of a brush and also had those metal-rolls for getting the air out. I have some bubbles on the flat surface. I figure, that i can sand them and put a batch of new fiberglass-fabric over it.
1909_boot3.jpg
But especially at the chine, i had no chance. There are bubbles all around the sharp edge of the corner.
1909_boot2.jpg
I am not sure, what to do about them. When I sand the area, then the fiberglass-tape will literally be cut in half and the tape should add more stability, which is imho impossible, when cut in half. On the other hand, how should i patch the corner. The Tape will not bend around the edge without bubbles, neither will the fabric. Is there a possibility to fill the bubbles with an injecton of some kind, the optics do not bother me? Or should i just put another layer of epoxi over it?

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Re: Roman´s OB15 (First Time Builder)

Post by pee wee » Fri Sep 20, 2019 9:16 am

Hi Roman; the regular way to do the chines is round them over after gluing but before the glass tape goes on; the tape won't go around a sharp corner, as you found out. After the fiberglass is all on, then you can build the corners up again to be sharp. For most of these designs the tape is an important structural part of the hull.

I know you're itching to make lots of progress, but I think you should wait until someone familiar with the plans can advise you on where to go from here.
Hank

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