smaller pitch or bigger diam prop?bf50 honda

[thefishingplumber]

Just fitted honda bf50 to my vimar 17ft motor boat. has std 11 1/4"x13"prop.at5500rpm wot i,m doing between 23-27mph depending on load. Go beachcombing carrying inflatable dinghy and diving kit so quite aload at times. have looked up forum but not sure direction to go.not concerned about actual top speed but want to have most suitable prop.my boats definately heavier than most 17ft so should I drop the pitch with same diam or less diam with similar pitch? normal load is about 1000kg ,boat, motors, fuel, kit ,people etc all in.It would appear from prop calculations there is as much as 20% slippage with std prop.
Any advice welcome.
ps tried new "ringprop" =17mph @wot,at least 6mph down.

 

[haskindm]

Re: smaller pitch or bigger diam prop?bf50 honda

The boat will go the speed that it will go with the proper prop. You have no choice. You need to select the prop that will put you in the proper RPM range at WOT. Since most outboards suggest between 5000 and 6000 RPM at WOT it sounds like maybe you already have the "best" prop for your boat. Find out what the maximum recoomended RPM is for your motor and test it under a "normal" load. If the boat reaches the recommended RPM at WOT there is nothing more that you can do; unless you want to buy an additional prop with a little less pitch to use when you are heavily loaded. NEVER run the engine at higher than the recomended maximum RPM.