Trojan Boat Forum

Sorry I have not responded to my own thread! The site stopped emailing me that there was a "topic notification". Anyway, When I got my boat it had the 14x10x1 prop. It would easily spin the props (starting from a stand still and gunning her) and at 3800-3900 rpm was not running very fast-had no gps so don't know exact. I could not rev her higher due to excessive vibration above about 3900 rpm. She would have easily turned more though I am sure. I then had 2" more pitch added to the prop. Still under propped. So I had a 14x16 cupped prop made which gave me a top speed on the gps at 3200 rpm WOT of 24 knots fresh water and 21 knots salt. Had considered a larger diameter prop, but there is not enuff clearance between the hull and prop. 14x16 was the foundry owners best estimate of what I needed. Should I take an inch of pitch out or go ahead and take two? Taking or adding more than 2" of pitch is not feasible.

Take out 2 but I think you may need to take out more if you can take out more you could remove the cup


You may want to check the tach to make sure it is correct also

Do you know if your prop has a cup? I experienced the same when I tried a prop without the cup, it acted just as you described, it would just slip and ventilate. Max I could get was around 23kts at 5000rpm,17 at 4000. I dropped one degree of pitch added the full cup and it made all the difference. If you still have your old prop 14x12 I would have a full cup added to it and give it a shot, it might surprise you, but just be warned over 25kts she is pretty squirrely.

As for taking an inch of prop out, the rule of thumb is 1" of prop ~200 rpm. I think we're pretty close in the power range 330hp, though you should have more torque. I had tried a 14x14 and max I could get was 3600rpm

There is no correct rule of thumb . any prop shop that says that I would walk out of It vares on the size of the prop taking 1 inch out of 10x10 prop will make about a 10% change . take 1 inch out of a 20x20 and make about a 5% change a lot of prop shops can do nice work but are clueless when it comes to telling you what you need.


I do agree putting some cup in the 14x12 may put you in the ball park . I believe 14x12 is close to where you need to be . what is the HP of the engine ?

I would also use a shop that can computer scan you prop.

I believe I am putting out about 340-360 hp. It really spun the 14x12. I am going to take two inches out of the 14x16 and see how that does. Then I can put (more?) cup into the 14x12

I understand a Bahamas cruising permit is around 200$good for a year. You will need passports and check US Customs regulation abou prior permission before return. Nota problem as well as all of the procedures are followed.

foofer b wrote:I believe I am putting out about 340-360 hp. It really spun the 14x12. I am going to take two inches out of the 14x16 and see how that does. Then I can put (more?) cup into the 14x12

Sounds like a good plan

Mpulsev/Rodman do you have your passports?

foofer b wrote:Mpulsev/Rodman do you have your passports?

Not yet, I will get mine soon.