Originally Posted by Warby12
Propulsion guy has just been! David O'Shea in Brisbane
, very happy
He said the prop is too big (diameter) for the engine. We ran the engine in the yard and he worked out the reduction of the transmission 1 to 1.7 and what prop should be in there. He adjusted the J-Prop to less pitch but said if this is still too much when back in the water there is room for one more reduction in pitch before it's time to start trimming the blades and put the pitch deeper again.
He also said on the Perkins
4018 I should be looking for max power at 3200 to 3500 revs.
Thanks again everyone for all of the help. Now it's onto removing the Vetus Flexible coupling which is seized on, may require another thread
Once it's off should I replace it with another fexible coupling or can I just buy a plan coupling off the shelf, Will it need to be machined?
Congrats on solving low rev problem.
Flex coupling or not? These are used for two reasons:
1. Allows for a bit of engine movement on it's flex mounts without bending shaft out of alignment & makes a more quiet drive line.
2. Should break before transmission or some other expensive component does if prop hits something or gets wound in rope
If you remove it,do you have enough excess shaft length o make up for it?
Flex couplings are an option-not a requirement,so it will be your choice.
Since you will be removing old flex coupling regardless,plan on checking your engine-shaft alignment,motor mounts,cutless bearing,etc.
Here is a link to Maine
Sail's excellent tech articles on a variety of things including shaft coupling machining & fitting,etc-good reading & reference.
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