The Beginning: Early Drawings

This is the first drawing I sent Bob Perry. The date on the drawing is March 19, 2012. I used the cad sub-program from my home design software to rough out a sail plan and layout plan. I couldn’t draw a full lines drawing but I did a midship section and set a prismatic coefficient that I was happy with to estimate the displacement.



The dotted red oval on the plan view is the area where I wanted full headroom. I wasn’t concerned about headroom further forward since that was seating area anyway and I wanted the lowest possible freeboard. The layout was taken from my 1984 Bill Lee designed Lancer 36. I was just thinking of a daysailor/day racer and was projecting a limited budget. My thinking was that it would be a cruising/racing boat for four guys, so everyone had their own bunk.

Notice the engine layout and the aft head. These never changed as the design progressed.

I admit, I have been obsessed with freeboard, trying to keep it as low as possible. In fact, I think when the new boat is loaded with fuel and water and extras, it will have 3’4″ freeboard, almost the same as my preliminary drawing. The new boat will be about 20,000″ loaded, which is heavier than I had wanted, but the new boat is bigger and better than the small one I started with. Bob did a terrific job working through all this.

Note the masthead rig on my drawing. I like to look at this drawing because it shows what Bob did with my first sketch.



For a special high resolution vector version of the above rendering in Acrobat format, please click this link: Dave drawing of the original 38′ LOD Daysailor

I was trying to keep the boat at just less than 40′ LOA.  Bob put his magic to work and we now had a preliminary sail plan, deck plan, accommodation plan, and a profile. Really a great looking boat.

Bob lancer layout

It was at this point that we decided more work was needed on the deck. We drew out the stern to make it a conventional transom with a walk through. You can see here that Bob is pushing me towards a fractional rig for lots of good reasons. I eventually came around to his point of view.

cooper perry 39.9 sail plan for web site rotate


By this point we have refined the deck plan with the conventionally raked transom with the walk through. I wanted more deck space aft, and did not see any need for a swim step for a Puget Sound boat. The walk through would be enough for dinghy access.  I was still trying to work out end boom sheeting-we had not solved this problem yet.

Bob lancer deck plan

When Bob had cleaned this up, we sent it out for bids and it came back much higher than we had anticipated. I gave up on the boat and bought a 1978 Tartan 37 with the intention of making it like new. It was very close to what I wanted, with the big drawback of no separate engine room, so it smelled like diesel down below and made my wife sick.

After I bought the Tartan my financial situation then did another 180 degree spin and a custom boat was feasible again. But with the cost of the boat higher than I had originally wanted to spend Bob talked me into a somewhat more conventional boat, with a more useful interior. It was a great idea on his part. I went back to work on Bob’s beautiful drawing with my crude drafting skills. I eliminated the port quarter berth in favor of a larger head further aft next to the companionway.


Here is Bob’s new interior drawing of what I wanted. Notice that we had to mirror image the interior because of the engine access on the port side.

bob saloon and galley

Now we are trying to improve the layout. The head is on the starboard side and the boat is 41’10”.  By this time I have moved the Tartan up to Edmonds Marina down the hill from my house and I have 50′ slip. This slip had the shortest waiting list and I was lucky to be able to move from Shilsole Marina in Seattle in only 8 months. After some experience sailing the 16.000# Tartan 37 I was feeling more comfortable with the idea of a some what larger boat, plus I realized it would be much easier to handle docking a 42′ boat into a 50′ slip than docking a 39.9′ boat into a 40′ slip. Here I am plugging away working on Bob’s drawing trying to perfect the interior accommodation.

bob near final interior

We had to mirror image the boat to move the starboard seat locker to the port side for access to the Volvo D2-55 engine. This was very close to the final design. The boat is now 42’11 inches long, although the water line is still the same. We added another 7 inches overhang in the final design  to perfect the cockpit and add a few inches to the J measurement of the fore triangle. The final LOA worked out to 43.56′. With the overhand of the bow roller and pulpit the boat should be just 44′. I had wanted a SA/D ration of 20, but I did not want too tall of a rig, so the extra length at the bow increased the J enough to get the 888 square foot sail area that I wanted.

I think the overhangs add a lot to the looks of the boat and I don’t mind that we give up 5% of potential LWL. We will get some of that back when the boat is in motion. I figure on a sailing length of 40′.

cooper perry 39.9 and cooper perry 43.35 sail plans evolution 2

Here you can see the effect of the longer LOA, even though the LWL is almost exactly the same. The displacement has gone up about a thousand pounds. We added a little more volume to the sections. This is still a light boat for a cruising 44′ footer. I am hoping to build the boat at 18,888# dry, with a 50% ballast/displacement ratio. Another 1000# for half load fuel, water, and stores would put the sailing displacement at about #20,000.

The boat is now 43.36 LOA.

The very last changes to the boat were to increase the beam at the deck level while leaving the beam at the water line exactly the same and add 3″ to the bow overhang to get the J length I wanted. The beam increased to 12′ from 11’6″, almost all of it amidships. Since we kept the cabin trunk exactly the same this gave us a little deck space with no performance penalty. This will make it a little easier to move forward and aft.

The final LOA is 43.56′ [not including bow roller or pulpit].