changed prop. 11-p form a 15-p

[55captain]

i have on now 11pich from a 15 pitch will i notice a speed difference at least will it be noticeable this is on a 55 hp 1978 Johnson that had recent work don link and sink and new tumbler and some wiring issues and rebuilt the carbs. still seems to be lacking power.like dragging a anchor big wake all so would it be to complicated to hook up tachometer my self please help me and thank you

 

[steelespike]

Re: changed prop. 11-p form a 15-p

We need a lot more than you have given us.Don't worry about being long winded but stick with the facts.The pitch change will add ABOUT 800 rpm.
Depending on the boat you should have excellent hole shot.An 11 is something you would put on a very heavy boat or a pontoon.
Speed will depend on how the 15 was doing.Please read the stickies at the top of the page.Your description sounds like perhaps a boat problem.
Perhaps the foam under the floor has absorbed water adding 100s of pounds near the stern where it really causes problems.maybe a very dirty bottom.A tinytach is reasonable and easy to install.
Describe your performance, hole shot time,best guess top speed.

 

[hwsiii]

Re: changed prop. 11-p form a 15-p

Captain, 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