KAAMA

32' Active Thunder conventional V-hull design...i.e. no steps and no notched transom, Stellings extention boxes, engines make peak HORSEPOWER at 5300-5400rpm, peak TORQUE is at 4400rpm.

With standard length stock Merc Bravo One XR drives, no nose cones with 32" lab finished Bravo 4-bladed props the boat runs about 89mph with about 1' chop. The boat will turn 5400rpm or so with these props.

MODS---Everything is the same except now swapped out standard Merc lower gearcases with -2" IMCO shorties w/nose cones which bring the propshaft centerlines up to about 1.5 to 2 inches below the bottom of the boat. Using the same Bravo 32" 4-blade props---RESULTS: Extremely difficult plaining, lost 7mph @3000rpm cruising speed and about 9mph @4000rpm and yet only gained MAYBE 1mph on top @WOT and WOT RPM remained the same. The only thing I liked about the IMCO -2" shorties so far is they gave the boat a little better angle of attack hence the boat's attitude rode a little flatter.

So far I am very dissappointed with the IMCO -2" shorties with the Bravo 32" props---thought I would definately gain 5-7mph, but it didn't happen. If I can recapture the midrange cruising speed back that I had with the Merc standard length gearcases without losing any top end speed I would be much happier. Crusing between 3000rpm and 3600rpm is usually about the norm for me.

I want my boat to plane off better, and I want my midrange constant cruising speeds back! With the info given, what size Hydromotive P5X would you recommend for my boat's hull type with the current power, etc. ??? Thanks, Mark

waybomb

Take the silencers off Mark. Your boat is too quiet. Pisses everybody off when you sneak up on 'em. The extra HP should get you over the top. Va--room.

KAAMA

Also Julie----I think I need to clarify/re-visit the above statement. Simply just regaining the mid range constant cruising speed while using the P5X as compared to the Bravo 1 32" prop will NOT make me much happier as I have stated above. If all the P5X (or ANY prop for that matter) can give me is my original constant cruising speed back, then I might as well remove the IMCO -2" shorties and re-install my stock standard length Merc lower gearcases and keep using the 32" Bravo one 4-blades as if was before!

If the PX5's don't show some real performance gains of at least 5mph on top at WOT without any losses in the cruising speed------OR if I don't gain at least 5mph in the constant cruising midrange of my boat vs what I had before without any losses in the top end, then it won't be worth it to me and I will remove the IMCO shorties and go back to the way I originally had the boat. Of course this would have to be WITHOUT ANY blow out/slip coming on plane. In other words---the P5X's are really going to have to impress me! I am at least willing to test them before I throw the towel into the ring.

By the way, calculations show that I am somewhere around 18% slip with the IMCO shorties and Bravo-1 32" props.

throttleup

Thank you for calling Mark.

Julie

Linster

Kaama,

Dont know if this helps, but on the 2 37's here the shorties hurt as well. It seems they worked better wih a 3/4' spacer on stock lowers. Seems like AT sets them up a little on the high side from the start which makes a good top end.

Good Luck