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Just kidding...I figured that would get a few of your attention to help answer me some propeller questions. Actually my boat only came with 1 propeller.
Being the typical " Gearhead" I have this badass blown V-Drive that I haven't even driven yet, and I'm already trying to figure out how to make it faster. Being this is my first V-Drive, I have a million questions, I'll limit this post to prop selection. Here in northern WV there are no other V-Drives within a million miles. I have half a dozen other boats ....v-8 I/O's, big outboards, blah, blah ,blah...For years I have played the prop game with all my other boats...even with my twin ford powered 45' houseboat. Always looking for that last little bit of speed. Changing the pitch, diameter,the rake ,getting a chopper ,raker , 3 blade, 4 blade, cupped, and every combination possible, looking for better hole-shot, bow lift, top end, tube pulling power etc, etc , etc.....
Now after reading different posts on here, and reading what people on here are running on their boat I have noticed something verry different from other types of boats. Everyone nearly uses the same prop or something verry close. My boat came with a menkens 11.5 by 15. I have noticed that a lot of boats run the same prop, even with verry different hp and weight boats, with the tuning being done with the gears in the v- drive. Is cup and rake not as important with a v- driven boat?? Is there speed to be gained by trying some different props??? The prop on my boat seems so small compared to the props I run on my other boats, yet it has twice the power. I'm new to this V- drive game , so someone please clue me in>>>>>
Thanks, Mike
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First, out drive and outboards have underdrive gear ratios, your v-drive has a overdrive ratio, therefore the prop is spinnning way faster than the motor. Outdrive and outboard props run slower than engine RPM, therefore need to be bigger with way more pitch than a v-drive. If v-drive used outboard sized props with underdrive ratios you prolly couldn't control the boat. V-drive flats are very sensitive to their props. Some advice, start collecting props if they are that hard to come by there
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Why not more pitch and less gear, or more gear and less pitch.
Thank you.
Gears are cheaper than props. Good props that is. And you are thinking this way to far.
If you state and engine size with given hp, they can give you a base recommendation as far as gearing and prop choice.
My boat is chrysler powered and it likes a taller gear with less rpm. BBC owners prefer more rpm and less gear given your motor makes peak hp in that range. So until you find your power range it really hard to give any suggestions.
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Thanks kindsvater, your on the right track. ... I also am wondering about slippage, and bow lift, and when does prop diameter come into play... Lets say I get the Drive geared perfect for my engines power band. What next?? Is there anymore to be gained with a different rake, or larger diameter...maybe I am reading into this to far.
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Rake
Higher Lift
More Rake, More Transom Lift
More bottom End
Pitch
Higher the Pitch, More Slip at Bottom End
Hook at Top End
Lower Pitch, more RPM
Diameter
Bigger Diameter, More Lift
More Torque, Less RPM
Thanks,
Heavyd
heavyd@dragboatcity.com
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Thanks Heavy D.. Also thanks for your website, for that is where I found my boat a couple of weeks ago for-sale. Great deals on there!
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There are lots and lots of varibles. As far as the prop goes once you find a prop that works for you then you stay with that prop and do your gear changes to get you in the rpm band you want. As far as the rest you got plate lengths, motor placement, strut angle, prop shaft lenth and so on. The list always continues. I'm actually the wrong one to ask. There are others with far more knowledge but if you get cocky with them or don't ask the right question you won't get an answer and you will moved into the club of Kim Hansen and Jim Anderson then you're focked.
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WV, you've been given some good advice so far. It's interesting that more rake has the opposite effect on a v-drive (tail lift) than on an OB or IO(bow lift) This is because it, in effect, moves the prop back. This is one of the variables Kflat mentioned- Move prop back= increased tail lift, move prop forward= increased bow lift. Also increased strut angle increases bow lift. The more power you add the further forward you can run the prop.
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