hi all im looking for some advice on prop sizing i have a 18ft bwm with a johnson v4 85 hp engine i use the boat for a bit of dohnuting and fast crusing what you recomend?
I recommend you post the following info so the prop gurus can help you:
Maximum recommended engine revs (or range)
Current maximum revs at wide open throttle (WOT)
Current maximum speed at WOT
Gear box ratio for your engine
Current prop size DIAM x PITCH, plus no of blades and Ali or S/S
I had a BWM Deepsea 17 with an 80 Yam and then a 90 Merc on the back and the best prop that I found was 13.75X17" alloy for general purpose with a 15" spare that I could also use if I had a heavy payload and needed some grunt.
I did a lot of experimenting with Stainless V's Alloy props and found virtually no difference in performance between the two. At the end of the day I chose the Alloy ones because they're cheaper to buy and if you hit an underwater obstruction then the prop is likely to take the impact protecting the gearbox a little.
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Andy
Looks Slow but is Fast
Member of the ebay Blue RIB cover club.
Assuming johnson and evinrude props are the same (downhilldai please advise) I have a 15'' and a couple of 16.5'' plus a 17'' all in stainless ,one of which may be suitable.
