prop recommendation?

[jaxbroker]

I just bought a 77 Wellcraft Skipjack 24 with twin 1986 evinrude 175's on a bracket. They have 14.25 x 23" sst props. I don't get good low-end performance and can't get on plane on one engine (2000 RPM max at 8mph). I am not into high top-end and mostly go offshore. I need better low-end control for fighting the waves. What pitch do you recommend? I'm thinking of a pair of 19's. Anyone interested in a trade-out? Thanks in advance.

 

[Spidybot]

Re: prop recommendation?

If one motor should cope with the full load it would need a very much lower pitch than when two motors are sharing the work.<br /><br />No matter what pitch is right for you, each motor of a pair is pitched to work as a part of a pair. Running on one only will make that one struggle to do the work of two and ofcourse not be able to cope.<br /><br />What rpm do you reach at WOT - running both?

 

[walleyehed]

Re: prop recommendation?

remember, you add 4" of pitch to the recommended prop size of what would be recommended for a single. If you are worried about running on one engine only-you cannot prop for both situations. You could go with 2 19's but you will lose alot of top-end, and only be able to operate at 1/2 throttle or less.<br /> The idea behind 2 engines is the same as in aviation, you still have 1 to get you in but in noway, the same speed......

 

[Hooty]

Re: prop recommendation?

How many revs are the engines turning at wfo?<br /><br />c/6<br /><br />Hooty

 

[walleyehed]

Re: prop recommendation?

....WFO???//HIGH-5 , HOOTY!!!!

 

[jaxbroker]

Re: prop recommendation?

I still haven't gotten to WOT yet. The props cavitate badly, lose their bite and the engine races to around 5500 rpm. I attributed that to the props being of too high a pitch. I am still getting used to adjusting the combination of motor trim/ trim tabs. The highest rpms I have attained yet is 4000, with the boat doing around 42mph. I don't have much holeshot and can't get easily onto plan offshore in small seas without fighting the cavitation. It seems I should be able to cruise around 25-30mph in 2-3' seas without much problem, but I can't. Does this seem reasonable? I am interested in a higher speed on one engine in case of breakdowns offshore, where 8mph doesn't cut it. Do I need to look into a third "emergency" prop to be switched out in case of breakdown?

 

[Dhadley]

Re: prop recommendation?

Where are the AV plates in relation to the hull? IE -- whats your X dimension on each?

 

[jaxbroker]

Re: prop recommendation?

I don't understand the question. The motors are on a bracket and sit about 24" off the transom. The plate above the props (I assume this is the av plate) is about in line with the bottom of the hull.