Gunboat Beam ...?

[Cheechako]

I was looking at a picture of a gunboat the other day.... just scaling by eye, it looks like the beam is closer to a third the length instead of half. Guess I should look it up... are they narrower than most?

[cat man do]

Took a couple of seconds
Gunboat 55 Specifications - Gunboat - Charleston, SC

[FSMike]

I think most cruising cat designers seem to narrow the beam when the loa gets over 50' or so.

[Sand crab]

Originally Posted by FSMike

I think most cruising cat designers seem to narrow the beam when the loa gets over 50' or so.

+1 The GB66 is 28'. I read somewhere that the somewhat normal 50% beam is less important as the boat gets bigger. Another statistic is the centerline of beam to centerline of beam width. On a slim hulled boat like this the centerlines are wider spaced than a normal fat cruiser hull.
http://www.gunboat.com/66-specs.php

[cat man do]

My 50ft cat in original form was 27.5 ft wide

The Slipstream 15

LOA 15.19m
LWL 14.51m
Beam 8.4m
Draft (boards up) 0.5m
Displacement 8400kg
Sail Areas Main 77.5sqm Jib 40.42sqm
Power sail drive diesel.
Strip Plank construction.

Modified for power, she's now 24ft wide

[Cheechako]

Originally Posted by FSMike

I think most cruising cat designers seem to narrow the beam when the loa gets over 50' or so.

Guess that makes sense, a SWB Jeep rolls over much easier than a LWB Caddillac!

[webejammin]

Even us little Gemini 105Mc cat owners know the width of the beam does not need to be half the length to be fast.

[cat man do]

Originally Posted by webejammin

Even us little Gemini 105Mc cat owners know the width of the beam does not need to be half the length to be fast.

What do you call fast?

My last 31 ft cruiser was 21 ft wide with about 60m2 of working sail, 70+ with genoa.
I reckon she would have had some hairy(er) moments if she had less beam.

[webejammin]

Originally Posted by cat man do

What do you call fast?

14kt's GPS against a 3kt current last spring

[cat man do]

Originally Posted by webejammin

14kt's against a 3kt current last spring

In 5 knots of wind or 50?

[webejammin]

Originally Posted by cat man do

In 5 knots of wind or 50?

Thunder storm with about 30kt's of breeze on a broad reach, no wind waves as we were close to shore just scooting along. We regularly sail at 10 to 12 kt's here on the Columbia river against a 2to 3 kt current along with the wind surfers flying around with kites.

I still want a Gunboat but it is too tall to sail here and go under the 65 ft bridges.