OD18 - NH

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Fair WX Pilot
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Re: OD18 - NH

Post by Fair WX Pilot » Fri Jan 27, 2017 12:40 am

A while ago I asked a question about the clamping board that Jamie was kind enough to post as I was having trouble with the forum.
I would like to replace the 2 x 8 clamping board on my OD18 with a laminated one. I am having trouble finding a suitable piece of material and feel this would be more stable and helps to keep the craft as light as possible. Weight is a big issue for me as I plan to put a lot in the boat and the prototype you built was probably quite a light boat.
Jacques was kind enough to respond.
From the designer: the industry standard (ABYC) calls for a transom thickness of 1.75" or more.
A 2x8 is 1.75" thick PLUS the transom plywood plus the fiberglass. I ran a 90 in bad weather during the tests and the transom was fine.
If you prefer plywood, this means 3 layers of 1/2" plus fiberglass. You can make the whole transom from 3 layers, no separate clamping board.

At the time of the design, quality hardwood was easily available but today it makes sense to use plywood which is what the majority of manufacturers still do. However, a quality 2x8 as specified is strong enough to take the specified engine.
Larry B posted a great picture of his transom lay-up with three laminations. If I had seen this before I started I would almost certainly have done the same but as I have already cut my transom out I am going to laminate my clamping board.

Just to make sure I did a quick experiment in the shop today with some offcuts to make sure I'm not adding loads of weight with the ply, all the data is approximate and doesn't include extra resin and glass etc. but I think it works:
Image
  • Solid clamping board = 504 in3
  • Laminated clamping board = 432 in3
  • Oak = 0.38 oz/in3
  • Pine = 0.22 oz/in3
  • Mahogany = 0.30 oz/in3
  • Meranti 1088 = 0.31 oz/in3
  • Oak clamping board = 24.6lbs
  • Pine clamping board = 10.7lbs
  • Mahogany clamping board = 25.6lbs
  • Plywood clamping board = 19.4lbs
:D
Last edited by Fair WX Pilot on Tue Jan 31, 2017 10:51 pm, edited 1 time in total.



Fair WX Pilot
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Re: OD18 - NH

Post by Fair WX Pilot » Fri Jan 27, 2017 4:06 pm

Spent the day cutting out the 12mm ply for the clamping board. It all seems to have gone well and now just needs bonding.
Image

I think the thickness should be just fine as it exceeds the 1.75" minimum but works out much lighter.
Image

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Re: OD18 - NH

Post by Jeff » Fri Jan 27, 2017 4:12 pm

Nice cuts Fair WX Pilot, but also a great shop to work in!!! Jeff

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Re: OD18 - NH

Post by Fair WX Pilot » Sun Jan 29, 2017 7:30 pm

A bit of a slow day in the shop today. I did get a couple of cabinets tided up and decided to throw away a lot of stuff I was keeping "just in case I needed it". I am marking time a bit as I have to be away for work next week and can't order any materials until I get back.

Cut out the butt splices and worked on layout. I found lots of posts on these so decided to do it a little different. As I have elected to laminate my stringers like a lot of people have. It changes the laminating schedule a little but fortunately I found the answers on the forum.
Jacques wrote in a Cracker Larry's post "2 layers of 1/2" is fine for the stringers. Thicker is better. If you use plywood stringers, you must tape them to the bottom or sole panel".
Cape Man wrote in his post "The tape is up in a few places along the edges of the butt blocks, as it makes the transition, but should have very little if any structural inferiority there".
With this in mind I decided to relieve the edges of the butt splices to help prevent the tape lifting using a panel raising bit in the table.
Image

I think this should help the tape transition from the splice to the bottom panel once I put a fillet along the edge.
Image

Image

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Re: OD18 - NH

Post by Fuzz » Sun Jan 29, 2017 8:15 pm

That is going to make glassing over the butt blocks much easier. Good move :D Just looking and watching tells me this is going to be one nice dory :wink:

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Re: OD18 - NH

Post by Browndog » Mon Jan 30, 2017 7:33 am

Really looking good. Fun to watch.

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cape man
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Re: OD18 - NH

Post by cape man » Mon Jan 30, 2017 11:11 am

That will help tremendously, and an easy step at this point. Like Fuzz, I think this is going to be a very nice Dory indeed. Mine was my first real build other than strip canoes, and in hind sight there are many things I have learned since that would have made her better and lighter. Some may think you calculating and weighing the clamping boards a bit anal, but everything you add to a boat weighs something. A pound here, and a pound there, and before you know it she's a fatty! :lol: :lol:

You do realize of course that taping the stringers and bulkheads add weight 8) 8) However, when running hard, straight into a tight chop at 25kts the teeth chattering doesn't concern me at all as I know those stringers and bulkheads are solid.
The world always seems brighter when you've just made something that wasn't there before - Neil Gaiman

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Re: OD18 - NH

Post by BB Sig » Mon Jan 30, 2017 11:27 am

How do you like your dust collector? Is it a Dust Right?

Fair WX Pilot
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Re: OD18 - NH

Post by Fair WX Pilot » Tue Jan 31, 2017 10:57 pm

How do you like your dust collector? Is it a Dust Right?
It is a Dust Right and I don't like it. It lets way too much fine dust through to the filter. I would never buy another one. I used to have a Dust Deputy which I brought as a stop gap when I built the shop until I could re-install the plumbed in system from my last shop. It worked so well I never got around to installing a 4" system. Unfortunately after eight years of service it broke a couple of weeks ago and I couldn't find another one so I got this and have regretted it ever since. The Dust Deputy was fantastic and at only $60 who could complain.

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Re: OD18 - NH

Post by Newt » Wed Feb 01, 2017 10:26 pm

The Dust Deputy seems to still be available.

http://www.bing.com/search?q=dust+deput ... =QBLH&sp=1

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