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Billy Martin

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I have a 87 topaz 29 with tamd

I have a 87 topaz 29 with tamd41a 200 hp engines with 1:93 gear/1-3/8 shafts. I am turning 3700 rpms at wot and 3200 with 20 knot cruise. I have 18x22 3 blade props and would like to know if I could increase my cruise speed without killing the motors by changinging the pitch. will 4 blade props help and whats the difference in3 vs 4. Thanks for any info.
 
"Calculating it up there seems

"Calculating it up there seems to be something severely wrong.
22" pitch should give a nominal speed of above 34 knots at 3700, and about 27 in 'GPS'/real.
At 3200RPM, nominal would be around 30Knots, given a 'GPS'/true around 24 as a 'worst case'.
I guess You are running a low quality prop with little efficiency, or Your boat has a serious 'drag' pulling up the slip.
My guess would be to go a 19" x 20" x 4(blade) and maximize the prop area.
What brand and type do You have today?"
 
"Thanks for the info Morten, I

"Thanks for the info Morten, I am not sure,I just bought the boat and havent had time to haul up and check on the props yet. These are the original props and I am going by the hand written notes in the shop manual by the original owner as per sizes."
 
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