Prop Suggestion

[jd438]

I have yet another prop question. Here's what I am working with.
Had a Michigan wheel 12 3/4" x 21p aluminum prop on a 1989 70hp mercury with t/t. That is on a 16' sylvan aluminum deep-v boat with console. Bumped a submerged stump just at low speed(5-6mph). Broke the prop. The boat had ok performance, the hole shot was a little slower than I want, but got up to around 32-34 mph running 4900 rpm. Thinking about putting a stainless prop on it, and going down to a 13 x 19p. I have a new hydrofoil that will go on as well. I would like to improve my hole shot and not lose any top end. Will this work for me?

 

[SteuryLover]

Re: Prop Suggestion

Im sure you will get some of the other guys to jump in here and get more specific on the prop. I just wanted to share my recent experience with a hydrofoil. I noticed you mentioned you do not want to compromise speed. I have a Merc 150 on a deep V 18' glass center console which is a different beast then yours I know. Last week I pulled off the hydrofoil that came on the motor when I bought it. In my case I gained 3-4 MPH top end and seems to be easier to steer at higher speeds as well. I am leaving the foil off. Most people here will tell you smart tabs for around $100 will do what you want the hydrofoil to do without the loss of top end and the extra strain on the outboards lower unit. Im sure there are good prop designs for your application out there that can meet your needs without any tabs or foil. Just my 2 cents.

 

[hwsiii]

Re: Prop Suggestion

Steury, you are 100% right in both cases a hydrofoil just eats speed up and an actually create problems at higher speeds.
Jd, I will be glad to help you but I need information to do that, here is what I need.


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
2a.What is the recommended HP for your 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 IMPORTANT
7A If you have a mercruiser and don?t know the ratio get your serial off the outdrive and go here http://www.sterndrives.com/mercruisersterndrives.html
8. Manufacturer?s recommended Wide Open Throttle (WOT) range
9. Anti-ventilation Plate height above keel of boat if it is an outboard in inches
10. Is it a bass boat or does it have a pad bottom
11. Does it have a hydrafoil, dolefin or trim tabs
12. Make, model, diameter, pitch and whether SS or aluminum prop
13. WOT RPM and speed from your current prop and how much gas and how many people were in the boat for the test data and is the speed by GPS. If you do not have a tach you can buy a Tiny Tach for $ 50
14. Are you at sea level or a higher elevation, give us the elevation in feet
15. Has your motor been tuned up lately and have you checked that the carburetor butterfly is opening all the way, checked compression, and looked at the plugs and checked spark, all of the forgoing could be the reason your prop is not attaining full RPM
16. How long has this prop been on the boat and why, at this time, do you think it is the wrong prop
17. Does the prop show any damage that you can see
18. What problems are you trying to cure or what are you looking for the boat to do that it is not doing the way you think it should or to your expectations

REMEMBER, The numbers I give you will be NO better than the information you give me

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