which props for 38 scarab flat deck
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which props for 38 scarab flat deck
I have a 38 scarab kv with ssm IV drives with 2" spacer and a 18x29 4 blade cleaver prop with about 550hp it seems like it takes forever to get on plane about 30mph do i have too big of prop not enough hp not enough k plane 380 or too deep in water or just dont know how to drive once boat is on plane it runs great just maybe not fast enough 65@5000. To get on plane just set rpm at about 3000 kplanes and drives down and wait for props to hook up.
Ps straight bottom hull.
engine originally was 1987 575 hpmercury racing but has been rebuilt with hydraulic roller cam do not know which cam it has was just guessing on hp. Its a 540 tall deck with team g intake and dominator carb. Its supposed to be original except for full roller hydraulic cam set up.
and i'm not sure on x dimension also has stelling extension boxes and headers
Ps straight bottom hull.
engine originally was 1987 575 hpmercury racing but has been rebuilt with hydraulic roller cam do not know which cam it has was just guessing on hp. Its a 540 tall deck with team g intake and dominator carb. Its supposed to be original except for full roller hydraulic cam set up.
and i'm not sure on x dimension also has stelling extension boxes and headers
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#3
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Ruducing the propelller diameter 1/2" should help the cause.
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Brett Anderson / BBLADES Professional Propellers
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Brett Anderson / BBLADES Professional Propellers
920-295-4435 http://www.bblades.com/
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i have a 1982 38 kv scarab. 572 tall decks ,dyno'd shows 630 hp at 5300 with flat tappet cam.( im turning labbed 15 1/4 x 25) to set the boat up rite you should pull a motor and get it on a dyno. it will tell you your peak hp rpms. you want to hit that rpm wfo nothing less and nothing more. its better for the motors and you get to sqweeze every mph out you can get. these scarabs straight bottoms are heavy boats, hence a light boat might turn a 30" prop with your power and a heavy boat might only turn 25" prop. my guess is -your props are way to big. with a hydrolic roller cam you should be turning at least 5500 rpm. but i would get that checked. by the way your boat looks SWEAT.
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Reducing diameter is a sizable job if done correctly. It is easy to lop off a 1/2". However, the correct process involves matching the the blade area to the new diameter. Also the thicknesses need to be adjusted when the diameter is reduced. We have the ability toi do these adjustments.
My suggestion to reduce diameter is focused on the planing issues. Diameter reductions will increase rpm and will change boat attitude. I believe it will help in your situation.
Ultimately the previous poster is correct in that you need to also know the best rpm for your engine HP operation. if it is low 5000's, reduce the diameter 1/2" and then learn from the results.
My suggestion to reduce diameter is focused on the planing issues. Diameter reductions will increase rpm and will change boat attitude. I believe it will help in your situation.
Ultimately the previous poster is correct in that you need to also know the best rpm for your engine HP operation. if it is low 5000's, reduce the diameter 1/2" and then learn from the results.
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Brett Anderson / BBLADES Professional Propellers
920-295-4435 http://www.bblades.com/
[email protected]
Brett Anderson / BBLADES Professional Propellers
920-295-4435 http://www.bblades.com/
[email protected]
#7
Hi Bret, I have the boat in question in my shop right now and am doing all the work for Bob (kvscarab38). I have a set of 26 inch Merc Racing 5 blades that have been cut down a bit (to 16 an 1/4 or 1/2 i think) they were off #6's so i will need to get a spacer but we were going to try them in the spring. would these be a good prop for this boat? our plan is to do some testing with spacers and props in the spring to get some baseline numbers than tune from there. Thanks for your input
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Throttles- Cleveland Construction 377 Talon
08 OPA Class 1 National Champion
08 Class 1 Geico Triple Crown Champion
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Throttles- Cleveland Construction 377 Talon
08 OPA Class 1 National Champion
08 Class 1 Geico Triple Crown Champion
08 OPA High Points Champion
10 OPA Class 1 National Champion ( happy now Ed! )
Last edited by glassdave; 01-05-2008 at 04:03 PM.
#9
oops . . . . forgot that tidbit of info. i will check them on monday
__________________
Throttles- Cleveland Construction 377 Talon
08 OPA Class 1 National Champion
08 Class 1 Geico Triple Crown Champion
08 OPA High Points Champion
10 OPA Class 1 National Champion ( happy now Ed! )
Throttles- Cleveland Construction 377 Talon
08 OPA Class 1 National Champion
08 Class 1 Geico Triple Crown Champion
08 OPA High Points Champion
10 OPA Class 1 National Champion ( happy now Ed! )
#10
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Hi Dave,
I think the first set of props are 18x29's and your props you said are 16.5ishx26. There is a large difference between the two. The small diameter will teach you something as far as planing but the 3" pitch difference also comes into the equation. The best advice would be to try everything you have available (carefully) and write down the results. With reading between the lines, we can head in the correct direction.
I think the first set of props are 18x29's and your props you said are 16.5ishx26. There is a large difference between the two. The small diameter will teach you something as far as planing but the 3" pitch difference also comes into the equation. The best advice would be to try everything you have available (carefully) and write down the results. With reading between the lines, we can head in the correct direction.
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Brett Anderson / BBLADES Professional Propellers
920-295-4435 http://www.bblades.com/
[email protected]
Brett Anderson / BBLADES Professional Propellers
920-295-4435 http://www.bblades.com/
[email protected]