Another Prop Question...

[Weekend Fisher]

Currently own 2004 Lund 1800ProV with a 2003 Evinrude Ficht 150HP motor running a 18" Pitch Raker Stainless prop. My issue is that I can currently blow by the 5250 rpm recommended limit. With full gear, full gas and livewells, my top end is only 42mph on the gps. My concern is that I can over rev the motor with a full weight load. Inversely, as my load is lightened, the problem is worstened by the fact that I hit max rpm sooner. Is my prop under pitched or not running right?? All of the calculators recommended by other members show that this boat motor combo should be dialed in with a 19" pitch prop and top speed should top at approx. 48mph at WOT. Going to a 19" prop by calculations would only reduce my rpm's at WOT by 100rpm? If I was to trim completely out and WOT, I am sure I would hit past 5500 rpm. All I can confirm is that I am not fully trimmed out and throttle is not wide open and the tach says 5250. Could my tachometer be out of calibration? It is just surprising that with such a heavy load, I can still over rev the motor with a 18" pitch prop....

[staylor]

...I run a Starcraft Superfisherman 176 w/150 Opti. This boat is rigged light and I run a 21 inch 3 or 4 blade prop most of the time, a 23 when I'm running very light. I see no reason why you can't spin a 20 inch Raker. This should keep your rpm down at light loads and higher speeds. If it bogs down with heavy loads then just go back to the 18 for the day. This is similar to rigs that take the family out water skiing. Normally you drop down 2 inches in pitch when its time to ski. As for trim, you can always over-rev any walleye rig by trimming out so far that the motor vents the prop. The key is to find the trim position that gives you the best speed without porpoising and check the rpm at that trim position.
Doug

[bvs]

There are more parameters to props than pitch. Number of blades, diamater, rake, and cupping can make a big difference as well. Also, not all motors and hulls are behave the same.

Go to a 20" Raker and you probably won't hit the rev limit anymore. Hold onto the 18" prop though. If you ever want to fish at a higher elevation or pull anyone behind your boat you'll be glad you have it.

On my boat and at my elevation I hit the rev limit with 15 inch prop at 6100RPM. I switched to a 17 inch in the exact same series and can only make 5300RPM. Holeshot and top speed are much better with the 15.

[Uncle Paul]

Take a look at your #s again The recommended range is something like 5500-6000 ( I don’t have the book in front of me) for that motor and if you are running at 5250 you are way to low on RPMs.Recheck the #s and you will probably find that the 18 pitch is the prop you need, run that motor closer to the top of the recommended RPM.Paul

[PJM]

Weekend Fisher

Like Uncle Paul said, the rpm range is closer to 6000 rpm on max. If you do a search on 1800 ProV you see a lot of guys are running props closer to 21p depending on the set up of course. The boat weight is like 1550 lb for just the boat and Staylor's boat is much lighter so it is hard to compare. Seahore can give you the exact rpm range if he sees this post or send him a PM.

[Weekend Fisher]

Thanks for all the great feedback. Checked the numbers again and indeed the RPM range for the 2003 Evinrude 150hp Ram Ficht is 4750-5250rpm. Strangely enough, the 175hp with the same gear ratio spins from 5250-5750rpm. I thought is was pretty low given what all the other manufacturer 150hp's spin at. I will definitely look into finding a 20" Raker and see how it works, but definitely hold onto the 18". It really pushes you into the seat on hole shot...