16' Sailing Tender Conch Ad Libitum
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
|Design Number 133|
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 overall||16'-0"||4.88 m|
|Length datum waterline||15'-0"||4.57 m|
|Estimated structural weight||300 lbs.||136 kg.|
|Displacement, to DWL||850 lbs.||386 kg.|
|Displacement-length ratio||112|| |
|Sail area||108 sq. ft.||10.03 m2|
|Sail area-displacement ratio||19.26|| |
|Prismatic coefficient||.567|| |
|Pounds per inch immersion||247|| |
|Entrance half-angle||22°|| |
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.