16' Tahiti prop query

[pcmpete]

Here are my specs:
16' Tahiti ski boat with a Volvo AQ130c 130hp motor with a Volvo 270 outdrive. (not sure of weight)
The drive has a hydro fin on it, not sure if it helps or not
14x17 volvo prop
WOT 3000rpm max, should be 5000 ish
I cannot get this boat over 20mph (GPS)

Is this the right prop or do I have other issues?

Thanks for your time.

PEte

 

[steelespike]

Re: 16' Tahiti prop query

I would think a 17 would probably be a little light and would normally over rev.
Speed with a healthy motor the right prop would probably be over 40.
Lose the fin for now until you solve this then throw it away.
I would suspect a motor issue. Couple of easy checks.Does the throttle open all the way? are all the plug wires hooked up.Check the plugs do they
all look the same?While you have the plugs out check the compression.
Is the bottom clean?Let us know what you find.

 

[hwsiii]

Re: 16' Tahiti prop query

Steele is right in what he is saying, as always. We need the following information to provide the help you need.
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.

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

H

 

[pcmpete]

Re: 16' Tahiti prop query

I have tried researching this boat and have come up with nothing. But I will give as much info as I can:

1. Year, make and model of boat
1975 Schuster Tahiti

2. Length, width and base weight of boat, look for boat decal on back of boat
Length 16 foot, width 6 foot, weight unknown (HIN is TAH237690575)

3. Number of people and gallons of gas normally on boat
People, 3 Adults and approx 20 gallons of gas

4. What do you use the boat for
Cruising the lake, pulling knee board and a tube

5. Is it a Deep Vee and if so how many degrees of deadrise
Yes, I think it is a deep vee, not sure of the degrees

6. Year, make and model of motor
1975 Volvo AQ130c
7. HP and gear ratio of motor
130hp, ratio not sure, but should be standard for this combo

8. Manufacturer?s recommended WOT range
WOT should be 5000ish rpm

9. Antiventilation Plate height above keel of boat if it is an outboard in inches
Approx 10" below

10. Make, model, diameter, pitch and whether SS or aluminum prop
Volvo, 14" diameter, 17" pitch alumiuum

11. WOT RPM and speed from each prop
So far I can only get WOT of 3000rpm and 20mph


I hope this is enough info.

Thanking you in advance


Pete

 

[hwsiii]

Re: 16' Tahiti prop query

Pete, it appears to me you have a motor problem of some kind, check the timing, compression, spark at spark plugs and make sure butterfly in carburetor is opening completely fully horizontal. You are showing a 11% prop slip at 20 MPH and 3,000 RPM and that is about normal, but you are just not getting the HP to the prop because of the motor. You ought to be able to get about 37 MPH out of that boat and motor. I just made a guess on the weight of the boat. Here are the numbers.

Boat and Motor

Prop Picker

Prop Slip

H

 

[pcmpete]

Re: 16' Tahiti prop query

Thank you for the facts and figures, I will check your recommandations and will report back.

Thanks again

 

[hwsiii]

Re: 16' Tahiti prop query

You are welcome.

H

 

[thinksun]

Re: 16' Tahiti prop query

I have tried researching this boat and have come up with nothing. But I will give as much info as I can:

1. Year, make and model of boat
1975 Schuster Tahiti

2. Length, width and base weight of boat, look for boat decal on back of boat
Length 16 foot, width 6 foot, weight unknown (HIN is TAH237690575)

3. Number of people and gallons of gas normally on boat
People, 3 Adults and approx 20 gallons of gas

4. What do you use the boat for
Cruising the lake, pulling knee board and a tube

5. Is it a Deep Vee and if so how many degrees of deadrise
Yes, I think it is a deep vee, not sure of the degrees

6. Year, make and model of motor
1975 Volvo AQ130c
7. HP and gear ratio of motor
130hp, ratio not sure, but should be standard for this combo

8. Manufacturer?s recommended WOT range
WOT should be 5000ish rpm

9. Antiventilation Plate height above keel of boat if it is an outboard in inches
Approx 10" below

10. Make, model, diameter, pitch and whether SS or aluminum prop
Volvo, 14" diameter, 17" pitch alumiuum

11. WOT RPM and speed from each prop
So far I can only get WOT of 3000rpm and 20mph


I hope this is enough info.

Thanking you in advance


Pete

Tahiti is a Sidewinder splash. There are a few guys who have them and can give you details you are looking for here

 

[pcmpete]

Re: 16' Tahiti prop query

I think the Tahiti came slightly before the sidewinder but not 100% sure, I have just joined their forum so their feedback should be interesting.

Just a quick update on the motor performance issue, at WOT the butterfly in the carburetor was only opening to approx 75-80%. I have since adjusted it but have not had the chance to test on the water yet. Timing and compression is ok, but the have ordered tune up parts for the engine, points, rotor, cap etc....

Thanks again for your input.

 

[hwsiii]

Re: 16' Tahiti prop query

That is greatttt Pete.

H

 

[pcmpete]

Re: 16' Tahiti prop query - Update

Re: 16' Tahiti prop query - Update

Tuned up the motor, checked all the valve clearance and now I can get 4000rpm @ WOT and approx 35mph with the 14x17 prop.

 

[steelespike]

Re: 16' Tahiti prop query - Update

Re: 16' Tahiti prop query - Update

A great improvement but not 5,000 ish.Did you get rid of the fin?That could be good for a couple of mph and some rpm.Something like smart tabs would be a big improvement over the fin.Lose the fin,give her a test then decide if
you need tabs.

 

[hwsiii]

Re: 16' Tahiti prop query

Pete, your tach is wrong and you need to check it, you are showing negative prop slip and that is impossible.

H

 

[pcmpete]

Re: 16' Tahiti prop query

I just took the boat out again and checked the speed with GPS.

Results:
31mph @ 4000rpm

does this sound better?

What is the best way to check the tach?

I am considering an electronic ignition and a new coil, would these help?

Thanks again for your time.