Keel fairing on Attitude Adjustment
The keel fairing work I did on Attitude Adjustment, a 34-ft model I, gave the 160 Perkins an additional 250 rpm. This, I believe, is due to the fact that now the water can flow smoothly to the prop, where as the water normally flows with much turbulence due to the Mainship’s ‘fat’ keel.
This modification is very similar to how single engine ‘down easter's are currently being built. So the water flow theory must have merit.
In the Onelist Files:Keelfairing folder there are four sketches that I used to make the fairing blocks. These printed out at about 2/3 actual size for me so adjust accordingly if you use these.
I used a pressure treated 4 x 4 to make the blocks. These were pretty rough. Then I fitted them to the boat using a belt sander and very course grit. The lower block was easy; the upper took some time due to the curve.
I then removed the bottom paint from the aft section of the keel down to the gelcoat using a disc grinder. I attached the blocks using a thickened fiberglass resin mixture and held them in place with good old duct tape until cured.
The next step was to grind the keel down ahead of the blocks for about 12 inches or so. Using a disc grinder and belt sander, remove about ¼ inch or so, and taper it away from the blocks. Shape the blocks accordingly so they will be flush with the keel and hull.
I then glassed in the blocks using resin and 1 ½ ounce mat. I used 3 layers, each one overlapping farther forward. This takes some time waiting for the resin to dry, especially in CT in March. A heat gun or hairdryer with some plywood to block the wind helps speed the process.
After the three layers were cured, sand to smooth and use another application of thickened resin to fill in any low spots.
Then I applied three or four coats of gelcoat using a brush, wetsanded until smooth (nothing fussy), then bottom paint.
I estimate 10-12 hours for the job.
Jay Leonard
Attitude Adjustment
leonaj@torrington.com