16' Sailing Tender Conch Ad Libitum

Design Number 133

Conch Ad Libitum was commissioned by a family man who cruised with several active kids on a Grand Banks 36. He wanted a boat the kids could use for beachcombing that would be safe for them to use. The kids should be able to experience more about rowing and sailing in the new boat. The final requirement was that the new boat must be capable of being towed behind the GB36 at 9 knots between anchorages.

Paul Schweiss did an excellent job of building her and Dick Wagner did the first trials at his Old Boathouse in Seattle. I had a chance to sail her shortly afterwards. I agreed with Dick's conclusion that the long keel was not very good for tacking. We decided to add a daggerboard as the way to give her something on which to pivot.

This proved successful and she tacked well on it. In towing trials we decided she would need a cap for the daggerboard trunk too, to stop water spurting in there. This was held in place by the same shock cords that held the daggerboard. This sort of daggerboard trunk closure is well to fit on any boat that is to be towed or operated under outboard motor power. If reduces bailing later on and keeps the towing load on the painter light.

We gave her substantial scantlings to survive repeated beachings and other adventures. I reckoned her all-up weight came to a bit over 300 pounds, making her feel quite sturdy. Two adults could stand on her side decks and still have a couple of inches of freeboard left. She's quite safe for the lively young crewmembers climbing in and out of her, and when they are moving around her.

The spars stowed inside her, being designed shorter than the boat. We had a fitted cover made, and kept it in place, with the rudder, board, and rig all stowed inside for towing on a cruise.

Length overall16'-0"4.88 m
Length datum waterline15'-0"4.57 m
Beam5'-0"1.52 m
Draft0'-9"/3'-3"0.23/0.99 m
Freeboard:Forward1'-8"0.51 m
Least0'-10"0.25 m
Aft1'-30.38 m
Estimated structural weight300 lbs.136 kg.
Displacement, to DWL850 lbs.386 kg.
Displacement-length ratio112 
Sail area108 sq. ft.10.03 m2
Sail area-displacement ratio19.26 
Prismatic coefficient.567 
Pounds per inch immersion247 
Entrance half-angle22 

Note: The displacement numbers are calculated to the arbitrarily chosen DWL.
The calculated ratios of displacement-length and sail area-displacement will vary widely depending on the loading of the vessel.

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