Hi I'm just finishing getting my boat tuned since it came out of the water for the first time since we bought it (one year ago). It is unbelieveable how much was wrong, but anyway having serviced my 2 x 200hp Verado's, fixed a sticky valve, replaced spark plugs I got top speed up from 33 knots to 46.4 knots already @ 6000rpm
That all with the engines too low by two holes (2 inches)!!
So today they go back on - at the right height. Now the boat shop says (and Mercury UK says) I am probably under-propped and may well be redlining my engines at full speed/WOT and cavitating on acceleration. So chances are I need higher-geared props. It looked easy at first but suddenly I discovered Mercury Racing and their choice of 10 or more propellors, depending on boat type, natural bow lift, weight, whether you target top speed or efficiency etc.
My boat is 8 metres GRP rib, 300l fuel 70l water, probably 2 tons with engines? I don't know what "natural bow lift" is but my optimal trim used to be just shy of 10 degrees. I don't want to compromise top speed but I spend my time cruising at 4,000 in good weather (33 at the moment) and I think 3,000 / 22 knots or so once a breeze and chop comes into play, maybe the other 1/2 of the time we are out.
So do I get a Bravo 1 Verado, or a Cleaver style, can I get Lab Finish (low bow lift) or do I need Pro Finish (has more bow lift), is my boat light or "heavy", 3 blades or 4, Pro-Max in X7 steel looks to be nice. Any advice very welcome please? The exact pitch I will just base off of what I already have (unknown to me yet)
Of course I will do a sea trial this weekend if possible to find all my new RPM / Speed / Trim / lph / Range data with my newly correctly positioned existing props first. I secretly sort of hope the engines run out of revs right on 6,250 or 6,300 - just before the props run out of gearing - and then I can change nothing and would I have a 56mph boat! No complaining there. But 50 knots just sounds cool