I'm contemplaiting in adding a high performance nose cone to the engine. I have contacted my engineer and he says that although they may give more speed he knows of people complaining about cavitation (the prop not picking up much water).

Any suggestion advise much appreciated.

Thanks

PS I already have low water pick up and hydro jack plate fitted. Engine 150VMax Yamaha counter roatating props 25" pitch.

They are definitely application-specific.

There's just as much chance that you'll lose top speed as they is to gain.

I lost some acceleration and top end on an light outboard, but picked up a little stability. Also got more stable water pressure (the main reason it got the cone & lwp's).

My vote is to lightly glue it on, then go try it. If you like it, add some tack welds and fair it in permanently (remember to add weep holes for the trapped water to get out or you'll pop it off first good freeze). If you don't like it, take a wood mallet and knock it off. Lesson learned.

Thanks

on bravo 1 w/28 pitch& 30 pitch picked up 3 mph around 80 mph,made no difference when boat only went 62 w/23 pitch,also amplified chine walk until i added hydraulic steering,Smitty

Hi!

I adden a nose cone to my Promax 300 SVS. The engine is mounted on a Phantom 25, and the boat runs 78 mph at wot. There were no speed difference. Normally a nose cone steal speed below 85 mph. Merc reccommend their Sportmaster lower unit only for boats exceeding that speed. On the other hand, Bobs nose cone is normally faster since it use stock skeg that is thinner than the Sportmaster, and it has more bowlift built into it.

I will reccommend a stock lower unit below 82 mph. You should consider to add a torque tamer as it will compensate for crabbing.

Cheeers, Toffen

I added one to a 65 mph I/O...no difference in speed. On a positive note , I could turn harder at lower speed without the prop loosing it's bite. Previously at a slow plane (20 / 25 mph) if I turned relatively tight it would cavitate.

Well thanks very much guys. It has been very enlightening. I have decided to buy a BIG FOOT cone. Is very cheap so it will cost practically nothing to buy. Will try it and see what it does. If it doesn't work will take it off.
As it stand now I believe that with the counter rotatingh prop it has they make the boat to have very little to none chine walk and there is no any cavitation to speak of at tight turnings and at speed.
The boat is based on a Phantom 19 hull and with the 150VMax TRP and current set up makes up to 60-65 knots at WOT.
Thanks again for a very good advise