In Reply to: Re: Small Boat Design Concept... posted by Woodpecker on November 22, 2003 at 10:40:25:
Good observation Woodpecker. Yes, in the building of this design we did raise the transom height in anticipation of this concern. We also added a Motor Well Cover that is placed on top of the well, hugging the motor skeg, when the boat is underway. However, that still leaves a decent sized hole in the transom, and in the bottom of the boat, for the outboard to â€˜liveâ€™ in the wellâ€¦
So far the skiff responds quickly to oncoming waves at the transom, rising up and over even some steep 5 footers with their tops breaking a bit. We believe a number of factors contribute to this behavior. The motor weight is located AHEAD of the transom, not hung on the transom, and with the weight of boat gear and gas tank even ahead of the motor, the boats pitch motion from a stern wave is not slowed as it might be with say a heavy 4-cycle outboard hung on the transom and the attending gear -- battery, gas tank etc. -- all crowded in the stern. Also, this skiff has â€˜trailâ€™ to the bottom transom section. That is, the max beam is forward to the center of the boat and not at the stern. This presents a smaller transom target for the wave.
And perhaps, what makes it all work better is the â€˜trickâ€™ addition to the bottom mentioned in the first post. We have added a Port and Starboard sponson to either side (but apart) from the well. These are about 2 &1/2 inches deep, 10â€ wide, 6â€™ long or so and filled with foam then glassed. In calm water the boat actually â€˜skiesâ€™ on these sponsons. The sponsons have about 65 lbs of positive buoyancy each and effectively null the motor weight.
If water does get into the boat we of course have pumps. And, 2 transom drains that can be opened if the boat can maintain some headway.
The largest â€˜faultâ€™ with this design (aside from a rough ride at speed in a chop) does involve the same situation -- sliding down a wave bow first. The Pacific City Dory type has that turned up bow section and the corresponding bottom chine to go with it. As the boat picks up speed the bottom outside chine log is immersed and at the bottom of the wave the boat wants to â€˜hookâ€™ or attempt to trip and broach. One must be awake at the tiller and be ready to correct and add a bit of power to climb up onto the back of the next wave. If we were to build the boat again, we would eliminate the outside chine log, with its near 90 degree angle, and cover the chine area with a few layers of class tape smoothing this hard shaped angle to a rounded surface. This would not eliminate the tendency of the design to â€˜hookâ€™ put it would make the experience less aggressive.
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Topic - design concept - falk 04:20:47 11/18/03 (9)
- Re: design concept - falk 05:33:08 11/24/03 (0)
- Re: design concept - Woodpecker 12:18:13 11/19/03 (6)
- Re: design concept - falk 05:27:54 11/21/03 (5)
- Re: Small Boat Design Concept... - Thom V 18:08:56 11/21/03 (4)
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