Hi - I heard some great news from Michael (mmd) & wanted to share it with the forum. It's in the bilge 'cause 1) it ain't wood & 2) more will see it.
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Today was a good day.
The large lobster boat that I have been designer/project manager for these past many months was launched last Tuesday, and completed her sea trials today. The launch went without incident, and the trials have been more than could be expected.
As a baseline, lobster boats of this size (49'-2"' x 29' x 6') normally achieve a top speed of around 9.25 kts with engine power of between 650 and 800 hp. Theoretical hull speed is 9.4 kts. Our boat hit and held 10.5 kts. with a 550-hp engine.
In a turning test (at ½ throttle and running a straight course, put the helm hard over and turn 360 deg. without adjusting the throttle) the accepted norm for local lobster boats is to end the turn about 30 feet outside the origin point. Our boat sailed directly over its origin wake.
Finally, if the propeller is pitched correctly, at wide-open throttle (WOT) the engine rpms will be at the engine's rated rpm. Too low and the prop has too much pitch and the boat will be slow and fuel-greedy; if the engine over-revs, there is not enough pitch and the high revs will cause engine problems and the propeller is probably cavitating, which will cause pitting and loss of efficiency. Our boat's engine is rated as max rpm of 1800, and at trials today at WOT the engine reached and held 1795 rpm.
I am chuffed, the client - who said he would be pleased with anything over 8 kts and the accepted normal turning radius - is happy as a clam, and the builder (Boudreau's Boat Building Ltd, Morris Island, NS) is ecstatic.
All in all, a very satisfying day
(In the photo below, the builder - Jeramy Boudreau - is at far left, leaning on the “hay rail”; the proud owner - Justin Jacquard - is looking out the open window, and – best of all – the happy guy in the yellow ball cap is the local Transport Canada inspector who pronounced that “this is the best lobster boat I have been on in years!”)
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