WOT RPM's for my Inboard

[romertrain]

Will try to sum up this long story as best I can:

I can't seem to get the right prop on my 27' Cherokee inboard.

17x16.5 - 3700 RPM's WOT
14x10 - 6000 RPM's WOT
16x14 - 4900 RPM's WOT

The last one is close but I can't get on plane easily! Yes, I have trim tabs.
It's a single inboard 350 Crusader.

Why can't I get on plane and I'm only at 19 mph with the last prop.

thanks ahead of time.................romertrain

 

[steelespike]

Re: WOT RPM's for my Inboard

Is that a straight drive,no reduction?Could tell better with speeds and hole shot with each prop.Doesn't seem to be rhyme or reason on your prop selection.What is the rated rpm.

 

[Bifflefan]

Re: WOT RPM's for my Inboard

Like posted b4 me. need to know the rated RPM.
But i would stay away form 6000 with a V8. Unless its a race motor.
My guess would be 3500 to 4000 max for a sustained RPM. At 6000 thats a sure way to see the inside parts come outside for a look at the sunshine.
Stock rods will stretch at around 5500 RPM. Then its all down hill from there.

There's a saying in racing. "They run best, right before the blow".

 

[hwsiii]

Re: WOT RPM's for my Inboard

Romer, we will try to help you as much as we can, but there is certain information that is needed in order to help you. The following form has all of the information that is needed to help you with your problems finding the right prop. If you do not know all of the information that is asked for on the form please give us the most information you have available as I have a program I designed to find the right prop for any planning hull boat that needs this information, and anyone else who is trying to help you will need the same information. It requires time to find all this information when we have to look for it and in my defense I expect you to be willing to expend as much effort in finding the right prop as I do. We hope to be able to help you get the exact prop you need for your particular uses, and this information is required to do that.
It is not as simple to pick the right prop as most people coming to this forum think it is, that is why we ask so many questions, it is for your benefit we ask all these questions. And if you have a stainless steel prop or are changing to one the blade geometry of the prop can make a lot of difference in speed and RPM.

Iboats Boat and Motor Info

1. Year, make and model of boat
2. Length, width and base weight of boat, look for boat decal on back of boat
3. Number of people and gallons of gas normally on boat
4. What do you use the boat for
5. Is it a Deep Vee and if so how many degrees of deadrise
6. Year, make and model of motor
7. HP and gear ratio of motor
8. Manufacturer?s recommended WOT range
9. Antiventilation Plate height above keel of boat if it is an outboard in inches
10. Make, model, diameter, pitch and whether SS or aluminum prop
11. WOT RPM and speed from each prop
The only thing I ask of you is to come back and give me a report of WOT RPM and speed for my database.


H