Will a Hydrofoil help my setup?

[simplystressed]

Re: Will a Hydrofoil help my setup?

sounds like to me the water is hiting the cav plate... go up another hole ad go from there

I tried even on the highest setting last night...but didn't plane well when I did that. Got about 18mph on the GPS. Prop I think is 9 1/4 x 9 but will confirm later today.

 

[simplystressed]

Re: Will a Hydrofoil help my setup?

Just checked - prop is 9 1/4x9

 

[junior1113]

Re: Will a Hydrofoil help my setup?

iboats has a 9 1/4 x 7pitch 4 blade solas atima is only 57$. you cant beat a 4 blade prop thats all i run they grab more water and have beter push. another thing i would do is buy a mini tach to make sure we are in the right rpms range. 4 blade might might also make foil un needed.

 

[Jeep Man]

Re: Will a Hydrofoil help my setup?

get your self a preasure treated 2x2 (1 1/2x1 1/2)bolt to top of transom sealing it of course and id find an alluminum c plate to to go over the transom. the way it is now you have to much drag this will help. dont know how much.

Not a good idea to use PT with aluminium.

 

[simplystressed]

Re: Will a Hydrofoil help my setup?

No PT here guys no worries. So I'm going to try raising it up another inch and see what happens. I assume you don't want it spraying like that?

I'll also try moving the batteries to the back and see what it does.

Where would I get an RPM gauge?

As for a new prop, will the one mentioned 9 1/4 x 7pitch 4 blade improve speed as well?

 

[simplystressed]

Re: Will a Hydrofoil help my setup?

Raised it up another inch...way too high. Put it back down and its spraying bad off the AV plate on any setting that will remotely plane the boat. Should I lower it some more on the transom?

 

[simplystressed]

Re: Will a Hydrofoil help my setup?

Update guys. Water is still spraying off the AV plate, however I have a tiny-tach on order and should have some RPM numbers for you by mid-week. Hoping a new prop can get me moving better don't really want to get a 20 or 25hp if not necessary.

 

[simplystressed]

Re: Will a Hydrofoil help my setup?

Update - got my tinytach setup last night and was doing 5250rpm@18.5mph.

Two people in the boat, half a tank of gas. Should I be getting some more out of motor? Its just a 14ft vhull tin boat with the following load:

2 batteries (85lbs)
1 bowmount trolling motor (45lbs)
1 5 gallon tank of gas (40lbs)
fairly light wood floor & casting deck

Have both batteries and gas tank behind me so I realize I need to move something up front as well.

According to the manual 5500 is recommended RPM, iboats says 5500-6000. Should I go with a 7pitch 3blade instead or consider the 4blade 5pitch

 

[hwsiii]

Re: Will a Hydrofoil help my setup?

Hi hwsii, I was wondering if you could help recommend a prop for me. I've answered as much as i can below, let me know if there's anything else I can add to help. Thanks so much in advance.

Iboats Boat and Motor Info

1. Year, make and model of boat
95 Seanymph 14R

2. Length, width and base weight of boat, look for boat decal on back of boat
13.5ft, 62'' beam

3. Number of people and gallons of gas normally on boat
2 people, 5 gallon usually full. also 2 batteries, full floor and bowmount trolling motor the boat is 400lbs with gear, motor and gas not including persons.

4. What do you use the boat for
Fishing

5. Is it a Deep Vee and if so how many degrees of deadrise
Deep V

6. Year, make and model of motor
Suzuki DT15C 1990

7. HP and gear ratio of motor IMPORTANT
15 not sure of GR

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 WOT range
5500

9. Anti-ventilation Plate height above keel of boat if it is an outboard in inches
About Level

10. Is it a bass boat or does it have a pad bottom
No

11. Does it have a hydrafoil or trim tabs
No

12. Make, model, diameter, pitch and whether SS or aluminum prop
Stock 9 1/4 X 9 Aluminum

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
5250RPM@18.5mph. 2 people and 1/2 of a 5 gallon tank of gas. Always have 2 people.

14. Are you at sea level, or a much higher elevation
Around sea level

15. 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

Boat isn't planing well and I'd like to get some more speed out of it.

Simply, in my opinion you need to try and keep the most weight you can towards the stern of the boat. I show your motor has a gear ratio of 1.92:1, please verify this. Right now you are showing a prop slip of 21% which is not bad considering you have a power to weight ratio of about 70 to 1.Then you need a 4 blade Solas Amita 9 1/4 x 8" pitch prop from Iboats for less than $ 60. This prop will push the stern up and help lift the whole boat out of the water to create less drag, it will also increase your hole shot and acceleration through all RPM. Hopefully with this stern lifter you will not need anything else to help hold the boat up. I do not believe you will get very much more speed out of this setup unless you are able to move the motor up another notch on the transom.
Here are my numbers and possible projected prop slip with new prop and the new prop should be turning approximately 5600 RPM beause of the 4th blade.

Boat and Motor

Prop Slip

Prop Change

Price: $56.95
You Save: $19.05
Compare: $76.00
Discount: 25.1% Off
Add Amita Aluminum Propeller 4113-093-08 To Your Cart
IBOATS
Propeller Specifications:
SKU:#4113-093-08
Manufacturer: Solas
Brand: Amita
Material: Aluminum
Diameter: 9 - 1/4?
Pitch: 8?
Blades: 4
Rotation: Standard (Clockwise)
Usually Ships Within: 1 Business Day


H

 

[simplystressed]

Re: Will a Hydrofoil help my setup?

Thanks hwsiii! I verified with brownspoint that it is indeed a 1.92 ratio.

just 2 quick questions:

1. what is the difference between 4blade and 3blade? Any speed difference? Since I moved all the weight to the back AND moved the motor up on the transom it does seem to plane out much better. So maybe a 4blade isn't needed and can go with 3 for speed?
2. iboats lists my motor as being able to go to 6000RPM - or should we stick with 5500rpm as the max?

Again, many thanks for your help.

 

[hwsiii]

Re: Will a Hydrofoil help my setup?

Simply, for every 1 HP you have you are trying to move 70 pounds of weight across the water, the average boat has a power to weight ratio of 1 HP to about 25 pounds. That is a very small power to weight ratio and requires a lot of blade surface area to keep prop slip to a minimum, right now you have a prop slip of 21% in part because of this. You are very welcome to try a 3 blade and it might work for you, but in my opinion in most cases anything other than a stern lifting prop for an underpowered heavy vee hull form boat is a mistake. What you will gain in RPM you will lose in prop slip, and if you do get enough blade surface area in a 3 blade prop it will also lower your RPM just like the 4 blade. It would be nice to have the best of both worlds, and we can accomplish this if you are willing to buy a few props and we can do some testing with stainless steel until we get the right one for maximum speed.


H

 

[Mel Taylor]

Re: Will a Hydrofoil help my setup?

Oops

 

[simplystressed]

Re: Will a Hydrofoil help my setup?

Alright I'm ready to buy hwsii. One more question:

iboats says my motor can run up to 6000RPM (my 1990 manual says 5500). http://boatpropellers.iboats.com/Su...r=1990&**********=273856359&*******=760835741

Should I consider the 7pitch 4blade instead? What would be the pros/cons?

 

[hwsiii]

Re: Will a Hydrofoil help my setup?

Iboats is wrong stick with the 8" pith that is what you need.


H