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Post by Dick Thompson on Jul 1, 2014 10:21:55 GMT -5
Hey Guys,
Several members asked for a build thread on a new generation Thunderboat that I'm working on. Most of you guys know how to do construction, so I thought I'd start with how scratch plans are generated and turned into a finished boat. I don't have CAD skills, so this will be done by old fashioned drafting.
First, what is the goal?
Charlie Harrington has provided us with a valuable tool with the videos he takes. I looked at how my boat was riding and feel it still has more angle of attack than I would like. So, one goal is to lower the nose in the water. The plan is to reduce sponson height by 1/8".
Second, I'd like to improve cornering characteristics. The plan is to increase afterplane length by 1". The sponson transom will be moved ahead 1/2" and the rear hull will have 1/2" added. The added length of the after plane should in theory give more turning leverage between the rudder and turn fin. I'm hoping this will require less rudder input for the same turn radius, which reduces drag and increases corner speeds.
So, that's my plan - won't know if it works till I try it!!
So, Here are the elements of generating the plans.
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Post by Dick Thompson on Jul 1, 2014 10:47:09 GMT -5
First, plans will be drawn full size so templates can be generated and confirmed back against the plans. I get paper from commercial copy shops and they give me 30" wide by any length I want. For drawing tools, a sheetrock "T" square, 5' straight edge, triangles, french curves. The most used tool - a 4' X 1/8" square of Basswood and brass weights to loft long curves. I start with a side view, developing those details that can be generated. A arbitrary reference line is drawn bow to stern roughly in the middle of the view. This line will be also referenced when the front view is developed. Using dividers, the dimensions above and below the reference line are noted on the drawing. The measurements of the bulkhead stations are noted from a common point at the sponson transom bulkhead. Consider this reference line to be a horizontal slice through the hull.  |
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Post by Dick Thompson on Jul 1, 2014 11:20:46 GMT -5
Next the Top view is developed using the centerline as a vertical reference plane. Only half the hull is needed as I'm going to use mirror image in making the patterns. The Top view and Side View will be used to develop the very critical front view that will combine both horizontal and vertical planes. Attachments:
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Post by Dick Thompson on Jul 1, 2014 12:12:28 GMT -5
Next, The front view was developed, using both side and top references. Note the horizontal reference line in this view also. I stacked each bulkhead into one view. Then made multiple copies to use to cut out each template. This minimizes dimensional errors. Attachments:
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Post by Dick Thompson on Jul 1, 2014 13:22:19 GMT -5
After cutting out the forward templates, they are checked for accuracy against the side plan view. The template is slid along the reference line to pick up individual points against the side view.. Attachments:
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mps86
Junior Member
Posts: 63
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Post by mps86 on Jul 1, 2014 18:45:07 GMT -5
Good Stuff Dick! Really like the old school drafting. Easier on the eyes than staring at autocad all day!
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Post by Dick Thompson on Jul 1, 2014 18:51:19 GMT -5
Thanks Matt,
I'm just trying to give an overview of the process without causing eyes to glaze over..
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Post by Craig Mapstone on Jul 4, 2014 15:16:43 GMT -5
Dick, Thanks for taking the time to share this! Very interesting indeed!
Where do you get your plywood? And what do you have to look for as far as quality?
Thanks.
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Post by Dick Thompson on Jul 5, 2014 8:50:56 GMT -5
I build with "aircraft grade" plywood. It's not cheap, but with the thin ply layers it tends to cut more cleanly and it is stronger than standard grade. There is one source I buy from that has sheets 61" x 61" which gets away from splicing on a large hull. That Company is B&D International in Seattle Washington. Sheets can be shipped by UPS when cut in half.
This hull will use 2 MM on hull bottom and sponsons. Top deck on hull and sponsons is 1.5 MM. Sides and bulkheads are 3.0 MM
B&D is waiting on a supply of the 3 mm sheets and as soon as they are available I'll order what I need.
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Post by Dick Thompson on Jul 20, 2014 7:30:10 GMT -5
Well, while I'm waiting for the supplier to get the 3 MM plywood in stock, there is some 1/4" parts that can be made. Picked up a 12" x 24" sheet of 1/4" 5 Ply from the local craft store. Cut out the Engine Rails and Sponson Transom,layed out and drilled the engine mount holes. Dry fit everything together, then put the access cut outs in the Bulkhead and drilled for the Stuffing tube. Since I had all these points located on the plan, it was much easier to pre-drill before actual assembly.  |
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Post by Dick Thompson on Jul 20, 2014 7:32:41 GMT -5
Added pix Attachments:
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Post by Dick Thompson on Jul 20, 2014 17:21:26 GMT -5
Supplier tells me the 3.0 MM large sheets of ply won't be available for 2 to 3 more weeks. They are sending the thinner sheets that are in stock. 0rdered the 3.0 mm from Balsa USA. They have 12" x 48" panels available. I'll have to splice a few inches on the side panels, but at least things can start to move.
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mps86
Junior Member
Posts: 63
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Post by mps86 on Jul 20, 2014 18:46:29 GMT -5
Looks good Dick. See ya this weekend in Toronto.
Matt
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Post by Dick Thompson on Jul 21, 2014 21:18:03 GMT -5
2 12" x 48" sheets of 3 MM plywood came. Layed out the Side Panels on one sheet and the Bulkheads on the other. Next I'll statr cutting and dry fitting things together. A piece will have to be spliced in at the nose of the Sidemember as the 48" lengths are just that much too short. Attachments:
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Post by Dick Thompson on Jul 21, 2014 21:20:36 GMT -5
Bulkheads laid out on plywoood. Attachments:
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