BlueWave 16.5 Super Tunnel Prop?

[bleedingthumbs]

Boat has a 70hp Johnson outboard, and is usually fairly well loaded with a bait tank and 2 fisherman. Top speed( close to 5500rpm) is around 25mph. Can a different prop help here, or is it a jackplate that we need. Prop is a powertech prop, 3blades, stainless steel model numbers

318-688-1970
OM140red3r15p
934 3282

Thanks for any assistance, looking for a little better top end speed.

 

[hwsiii]

Re: BlueWave 16.5 Super Tunnel Prop?

Thumbs, can you tell me how big the tunnel is on this boat. I show a base weight of 850 pounds and a length of 16' and a beam of about 7' and an allup weight of about 1,900 pounds, is this correct?

H

 

[bleedingthumbs]

Re: BlueWave 16.5 Super Tunnel Prop?

Those numbers would be right on. Thanks.

 

[hwsiii]

Re: BlueWave 16.5 Super Tunnel Prop?

Thumbs, the first thing you should hek is how high the anti ventilation plate is above the tunnel in your boat, a lot of people don't realize that with a tunnel you are able to raise the motor much higher than normal. If you could take a picture that is exactly level with the antiventilation plate so we could tell how high the plate is above the tunnel it would help.
But if this is not possible you should purchase a Solas Amita 4 blade aluminum prop in a 13" x 15" size. This prop has stern lift which is needed very much by your tunnel hull to pick the stern up because of the tunnel and a larger surface area to reduce your Prop Slip which is at 21% right now with the Red3. What you purchased in the powertech Red3 prop was a moderate raked and cupped prop that is not really suitable for a tunnel hull like yours.

H

 

[bleedingthumbs]

Re: BlueWave 16.5 Super Tunnel Prop?

I will see if i can get some pics posted, boat is not stored near me, but will see if i can find any. Thanks for the help again.

 

[hwsiii]

Re: BlueWave 16.5 Super Tunnel Prop?

Thank you very much.

H

 

[Fleen]

Re: BlueWave 16.5 Super Tunnel Prop?

hwsiii,
What kind of top end speed improvement will this prop create if the boat now gets up to about 23mph?

Also, my Super Tunnel almost always leans to the left while running full out, any idea of what might be causing this? Anything to worry about?

Thanks

 

[Fleen]

Re: BlueWave 16.5 Super Tunnel Prop?

This is kinda a joint venture with bleedingthumbs by the way hwsiii. I am closer to the boat so Im takin the pics.

Pics of the anti-ventilation plate (I circled what I thought was it). Sits about 1-2" above the tunnel when trimmed approximately level. Also took a pic of a disc under that plate that has a small fin/rudder coming off of it. Just noticed it is number from 1-12 going both left and right. Its currently set on 1 to the right. Any chance this is the culprit to it riding to the right?

Many thanks for all the advice, sorry for the basket full of questions.

 

[bleedingthumbs]

Re: BlueWave 16.5 Super Tunnel Prop?

Thanks for getting those pics posted Fleen.

Do any of those pics help out hwsiii?

We may just need to find a place that will let us give a different prop a test drive.

 

[hwsiii]

Re: BlueWave 16.5 Super Tunnel Prop?

Thumbs you should take the Stingray fin off the anti cavitation plate and see if the boat leans left anymore. Then run it in opposite directions and give me a WOT RPM and top speed without the stingray. Fleen that fin is used for steering torque, it won't make the boat lean it is used to make the steering neutral so it doesn't pull to the right or left.
I am sorry but the grandkids are here right now and I am busy, I will make another post later tonight with more info. The pictures are great by the way Fleen, I will look at them later in detail. Don't worry about the questions I have just as many. LOL

H

 

[bleedingthumbs]

Re: BlueWave 16.5 Super Tunnel Prop?

No hurry, we wont be able to get the boat out for another week or so, but had planned on trying it without the hydrafoil. Right now top speed is 23mph, at 5400 rpm.

 

[hwsiii]

Re: BlueWave 16.5 Super Tunnel Prop?

You are showing a prop slip of 27% at 23 MPH and 5,400 RPM with that prop at this time. The sting ray can help getting on plane but on some boats it can slow the top speed down. I just had someone get a solas amita prop and it didn't do what I expected, we are trying to rule out mechanical problems at this time but don't do anything with the solas right now.
After y'all take it out with the fin off give me some RPM and speed readings starting at 3,000 RPM and every 500 RPM after that with a GPS if possible. Also give me the slowest planing RPM and speed that will hold the boat on plane. These will help on figuring prop slip at different RPM to see what is happening. I know this is a pain but it will help us in the long run, I also would like to know exactly how long and wide the tunnel is and is it rounded or square. I have a prop test sheet if that will help.

H

 

[bleedingthumbs]

Re: BlueWave 16.5 Super Tunnel Prop?

Sounds good, we will get it on the water in a week or so and get those measurements for you. It is a rounded tunnel, but will have to look to get the length of it. I will bump this up when we get the next round of info.

Again thanks for you help.

 

[hwsiii]

Re: BlueWave 16.5 Super Tunnel Prop?

You are very welcome.

H

 

[Fleen]

Re: BlueWave 16.5 Super Tunnel Prop?

OK, got some specs for ya.

Took the foil off and was able to get it up to 27 mph with the motor trimmed up. However, it was about a 200 lb lighter load than when it topped out at 23. Slowest rpm that will get boat on plane is 4000, trimmed all the way down. Speeds at each 500 rpm are as follows --- 3000rpm=7mph, 3500rpm=12mph, 4000rpm=21mph, 4500rpm=24mph. Those were all with the motor trimmed all the way down. Still seemed to lean a bit left. Got on plane quick, as usual. Conditions were a bit windy, about 16mph but I checked it both with and against the wind and it wasnt much different. Overall didnt seem to change muxh. Steering did seem smoother.

Hope that helps!

 

[hwsiii]

Re: BlueWave 16.5 Super Tunnel Prop?

At 4,500 RPM and 25 MPH you are showing a Prop Slip of only 9% now, instead of the 27% you were showing at 23 MPH and 5,400 RPM before. So you gained about 4 MPH by getting rid of the stingray, I don't believe the loss of 200 pounds in weight affected the speed more than 1 MPH at most, but you an add the extra 200 pounds next time and confirm that. But you didn't say what the RPM were at 27 MPH at WOT.
We are getting to where we will have it the best we can get shortly, we just need a prop change now, and figure out why it is leaning still.

H

 

[bleedingthumbs]

Re: BlueWave 16.5 Super Tunnel Prop?

I believe he told me it was right at 5400 at wot for 27mph, this prop stuff is confusing.

 

[Fleen]

Re: BlueWave 16.5 Super Tunnel Prop?

Sorry for the delay. Thumbs is correct, about 5400 at 27mph. Lean didn't seem as bad this time, but still there.

 

[hwsiii]

Re: BlueWave 16.5 Super Tunnel Prop?

Gentlemen, I don't know what is going on, but something is NOT RIGHT. On a normal boat prop slip does NOT go up as RPM increases, it goes DOWN. From 24 to 27 MPH you show a Prop Slip increase from 9% to 15%, which means something is drastically wrong with either the setup, prop or the boat, although it could be ventilation from the prop being to high in the water column. If this is the case then you should hear the difference in the sound of it ventilating. Next time when running the boat at WOT trim the motor down some, if it is ventilation, it should go away. Also check to see if the motor is aligned perfectly vertically. Check to see if there is excess weight or water in the port side of the boat, from bow to stern. Try to borrow a standard 15 or 17" Pitch aluminum propeller and try it with the boat, to rule out something wrong with the prop itself. If that is not the case then it could be the hull or the tunnel.


Prop Slip

I know you don't want to hear this but I believe it is a possibility it is the boat, that is why you are leaning to the left all the time. I believe it is possible that the hull was not correctly supported for a long period of time and that changed the hull form in a bad way.

If none of the above problems were found y'all need to get together at the boat and go over the entire bottom with a 36" steel ruler and a tape and draw a diagram of the port and starboard side with measurements from the keel showing depths and contour changes on the port side and on the starboard side, from the stern to about 50% forward. I believe there will be a noticeable change, once you have a diagram of the bottom that will be recognizable as the problem. Although the problem could be the tunnel itself.
What year tunnel hull is this boat. There are possible ways to correct this problem cheaply if you can find where the problem is.

H

 

[Fleen]

Re: BlueWave 16.5 Super Tunnel Prop?

OK, noticed something new today. The rudder is bent slightly. If you were standing behind it, looking at the motor, the bend is as if you grabbed the end closest to you and bent it left. Its an angle that would indeed make the boat veer left if its enough to effect it. Ill try to get a pic tomorrow.