55 foot power cat project
#71
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Hi Rik, thats what I thought. The RPM almost did go to 4.000. I have to look it up, but I think thats to high for Yanmar 6LY440's? Speed was arround 50 mph, but it felt faster, don't know if the meter is correct, have to double check. The boat used to hold 40 people and I think the props are chosen for that kind of weight.
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Looked at the manual, the engines high rpm is 4.200. Think they did that.
So I guess a higher pitch would be the way to go? Heard about a company in Miami that can bend the props to max 2 pitch higher, any experience with that?
So I guess a higher pitch would be the way to go? Heard about a company in Miami that can bend the props to max 2 pitch higher, any experience with that?
#73
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Your going to need some larger propellers.
The Yanmar 420/440/480's are a 3300 rpm engine.
Are you going to use the boat for yourself or to carry passengers?
The Yanmar 420/440/480's are a 3300 rpm engine.
Are you going to use the boat for yourself or to carry passengers?
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I'm going to use it for myself and my family. Will not be carrying around a lot of people with it like it used to do.
So basically you say go larger in size? They are 17.5 now.
So basically you say go larger in size? They are 17.5 now.
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What's the reduction ratio? Pitch?
Have you tried the rotation inboard instead of outboard?
Have you tried the rotation inboard instead of outboard?
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I have Yanmar 6LP's and they can spin to 4000, the recommended RPM with a full load is 3800. The 6LY's are a bigger motor and are not designed to spin as fast. 3300 as Rik said, if you get 3400 or 3500 with a very light boat in perfect conditions that is ok, but with a full load you should always be able to reach 3300 or you are overpropped.
Post some pics of it in the water!
Last edited by pstorti; 12-22-2015 at 08:03 AM.