Question about OB 15 plans.

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JMcGee
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Question about OB 15 plans.

Post by JMcGee » Tue Sep 17, 2019 1:30 pm

Just purchased the digital download for the OB 15. Looking at the the pdf files, there are a few size discrepancies. Between the metric version and the standard US version.

For anyone who has built this boat, which file did you create your patterns from?

I plan on using a CNC router in house to cut my plywood.



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steeps
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Re: Question about OB 15 plans.

Post by steeps » Tue Sep 17, 2019 1:32 pm

I had built an OB15 quite some time ago, I used the US measurements and did not have an issue.
hope this helps
and hope I can borrow your CNC machine one day :)

Jim

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Re: Question about OB 15 plans.

Post by Jaysen » Tue Sep 17, 2019 2:02 pm

remember that you don't need "accuracy" with the permanent ply. The plans/notes should tell you that you need a gap between panels and frame/sides. The real accuracy is needed in your jig/mold for the initial stitch of the hull (sometimes JM uses the frames as the jig).

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Marshall Moser
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Re: Question about OB 15 plans.

Post by Marshall Moser » Tue Sep 17, 2019 2:06 pm

If you're talking about discrepancies between the dimensions, can you site a specific example? Jacques will chime in, but his tolerance on the Imperial plans is probably around +/- 1/8". This is 3mm. Cutting by hand, this precision is unlikely. I'd use the metric plans to build my cut files.

Computer precision isn't necessary. Gaps will be filled with epoxy.

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Re: Question about OB 15 plans.

Post by Jeff » Tue Sep 17, 2019 2:26 pm

JMcGee, I sent Jacques a note to review your question and respond!! Jeff

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Capt UB
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Re: Question about OB 15 plans.

Post by Capt UB » Tue Sep 17, 2019 3:01 pm

JMcGee wrote:
Tue Sep 17, 2019 1:30 pm
Just purchased the digital download for the OB 15. Looking at the the pdf files, there are a few size discrepancies. Between the metric version and the standard US version.

For anyone who has built this boat, which file did you create your patterns from?

I plan on using a CNC router in house to cut my plywood.
I only use the metric version, much easier to add numbers up...
><((((º>¸.•´¯`•><((((º> ¸.•´¯`•.¸¸><((((º> ¸.•´¯`•.><((((º>

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Re: Question about OB 15 plans.

Post by Rtorres2411 » Tue Sep 17, 2019 10:57 pm

I used the US version and had no problems with my build. There is a section in this site that shows corrections to the OB 15 plans.
I pasted here those corrections.
OB15 dimensions
Revision after 15 years . . .
One of our builders brought the following to our attention:
- a small kink in the side panel
- a wrong location for the motorwell bulkhead.

Most builders will not notice any problem. They will fair the small kink with the batten and if they use the motorwell sides on the jig, as we state in the building notes, they will not need that location.
That is probably why we never heard of the dimensions mistakes.
However, the plans must be correct and here are the revisions.

For all plans sold before September 5th 2008:
- on drawing D107/6, side panel dimensions, the last one towards the bow before the tip should be 5" (126 mm), not 5-3/8".
- on drawing D107/5, motorwell location, distance from the transom is 20" (510 mm) not 2' 2". Note that that distance is given again on D107/3 and there it was correct. And again, try not to use that dimension, use the motorwell sides as we write in the building notes.
You can't go wrong that way.

If you did build your OB15 on a jig as we specify and if you used a fairing batten, everything was perfectly correct.

Hope this help.

Ruben
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72FDB8DC-52F5-4C07-99C1-0324733002FD.jpeg
2’2” should be 20” this is in plan D107/3

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Re: Question about OB 15 plans.

Post by jacquesmm » Wed Sep 18, 2019 9:21 am

JMcGee wrote:
Tue Sep 17, 2019 1:30 pm
Just purchased the digital download for the OB 15. Looking at the the pdf files, there are a few size discrepancies. Between the metric version and the standard US version.

For anyone who has built this boat, which file did you create your patterns from?

I plan on using a CNC router in house to cut my plywood.
Please list the discrepancies with drawing number. It is probably a dimensions tolerance difference, nothing to worry about.
The drawings are accurate within 5 decimals, the dimensions tolerance is set to 1/8" = 3 mm.
If you redraw for CNC, rebuild all your curves to the 2nd or 3rd degree with max. 5 vertices, never more and they will be fair.
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