Propping for 2" shorter lowers.
#11
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Do you have room in the box to go down?
Based on your numbers it seems as if you need to lower the drives.
Your boat relies on the drive and props to lift the bow. It does not have a lot of natural bow lift. If you raise the drives too high you will have to over trim in an attempt to get the bow up, this results in a rooster tail and part of the thrust of the props is being used to push the stern down instead of pushing the boat forward. By lowering the drives you won't have to trim as high so all the thrust from the prop is pushing the boat forward.
If you can lower the boxes I would do that and see what the results are before spending the money on new lowers. The boat will get on plane better, cruise speed will increase and handling will improve. It won't cost you anything but time. I wouldn't be surprised if you saw an increase in top end speed.
Matt
Based on your numbers it seems as if you need to lower the drives.
Your boat relies on the drive and props to lift the bow. It does not have a lot of natural bow lift. If you raise the drives too high you will have to over trim in an attempt to get the bow up, this results in a rooster tail and part of the thrust of the props is being used to push the stern down instead of pushing the boat forward. By lowering the drives you won't have to trim as high so all the thrust from the prop is pushing the boat forward.
If you can lower the boxes I would do that and see what the results are before spending the money on new lowers. The boat will get on plane better, cruise speed will increase and handling will improve. It won't cost you anything but time. I wouldn't be surprised if you saw an increase in top end speed.
Matt
#12
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I'm not so sure lowering the drives is the best idea either. (That dosn't mean don't try it if possible.) The numbers with the 32 Maximus (86.2@4900,1.5gr), your new numbers, are under 13% slip. For your boat, this isn't bad. Like Julie said in an earlier post on this thread (figuring 31 pitch) "9% is great." Lowering the drives will decrease the rpm with the 5 blades from 48-4900 to ?? It will also increase the drag from the gear case and propeller. Going deeper may require 4 blade propellers. I don't believe your current 4 blade is a great example.
What is the serial # code on the Maximus? Do you see the diameter stamped on the hub? There may be something we can do to the current 32 Max props to get you over the 5000 mark. With additional rpm, hopefully speed and boat attitude will change also improving the efficiency. Or, we have 30 Maximus props you can try and we can work from there.
Speaking of $69K ? What is your ultimate goal? Speed?
What is the serial # code on the Maximus? Do you see the diameter stamped on the hub? There may be something we can do to the current 32 Max props to get you over the 5000 mark. With additional rpm, hopefully speed and boat attitude will change also improving the efficiency. Or, we have 30 Maximus props you can try and we can work from there.
Speaking of $69K ? What is your ultimate goal? Speed?
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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]