Prop Recommendation

[Esox]

This is my first post so hopefully I?’ll get this right. I have a new to me ?’97 Lund 1850 Tyee with a ?‘97 150HP Johnson FICHT and 15HP honda kicker. The boat came with an AL 14.5x19 prop. Two blades on that prop were gouged so I replaced the prop with a 14.5x19 Michigan Wheel Ballistic (uninformed purchase). With the new prop I lost RPM so at WOT it was only turning 4600 Rpm @ 44Mph (GPS). I moved the engine up one hole and had gained a 100 Rpm and 2Mph. I went ahead and moved the engine up one more hole so it?’s now in the third hole. It now turns 5000 Rpm @ 47.6Mph (GPS). This is the first boat I?’ve had with power trim so I?’m not sure if this is normal but I can trim the engine all the way out. The exhaust seems to get loud at about 1/2 trim and it sounds like the prop is venting? and if I keep trimming it out it continues to gain Rpm and speed. Most of my initial testing was on fairly flat water but I had the boat out in some pretty rough water 2 weeks ago and was experiencing some venting on the hole shot (trim all the way in), at WOT and on turns (trimmed all the way out). I feel that the ballistic prop is not a good choice for this application and I also need to pick up another 500 Rpm to get 5500 Rpm at WOT. Also it seems like the ballistic doesn?’t provide enough lift for this boat. I?’m looking for suggestions on choosing a prop for this application. Any help is appreciated. Thank you.

 

[Dhadley]

Re: Prop Recommendation

It would seem that a 19" prop on that boat is a good choice. The Ballistic is not my favorite either but let's see if we can make it work, or at least improve on it.

If you can trim all the way and still stay hooked up then the general rule of thumb is that you can go up with the motor another hole. I'd suggest we try that.

In rough water and in tight turns you may need to trim down some. That's not unusual. And your cruise trim setting may not be the same as the wide open setting. You may have to trim down a bit in rough water also.

Once you get to a certian height with any prop you'll gain rpm but lose speed at or near the top of the trim range. When that happens the prop is venting and you've reached the max height (X dimension) for that prop.

 

[Esox]

Re: Prop Recommendation

Thanks for the reply Dhadley. I will raise the engine up one more hole which is the last hole and retest it. One other question I have is should I be worried about water pressure? I don't have a water pressure gauge but was thinking I should probably install one.

 

[Dhadley]

Re: Prop Recommendation

I'd suggest getting one. Then retest as is, that will establish the baseline water pressure. Good idea.

The other thing is -- when you do test this prop at more height we're not really concerned about the prop venting on take off or in tight corners at trim. We're just looking for the basic straight line differences - mainly speed & rpm.

 

[Esox]

Re: Prop Recommendation

Installed the water pressure guage today and went out to test it. Also brought a laptop along to verify the tach. Turns out the tach is approx 100 rpm off. Here are my results....all runs were made at full trim.

Water pressure @ idle: 2 psi.

1st. Run
46.5 mph
5000 rpm
22 psi water

2nd Run
47.1 mph
5000rpm
22 psi water

3rd Run
46.8 mph
5000rpm
22 psi water

Looks like I'm good on water pressure. It throws a 2' - 2.5' rooster tail at WOT and full trim. Seems to lack bow lift. When I got home I raised the engine to the last hole. Tomorrow I am going out to test it. Will post results tomorrow.

 

[Esox]

Re: Prop Recommendation

Here are the results from todays test runs. Engine mounted in the last hole.

1st Run
47.4 mph
5100 rpm
22 psi water

2nd Run
47.7 mph
5100 rpm
22 psi water

3rd Run
47.8 mph
5100 rpm
22psi water

I was able to trim the engine a little too much this time out. The rpm's would climb to 5200 and speed would fall off to 46+/- mph. Also it feels like there isn't as much bow lift as before.

 

[Crownie2]

Re: Prop Recommendation

I was going to say play with the trim to find the sweet spot, but it looks like you did that.

IMO, good results. You gained almost 1 MPH by going up. now you can decide if the reported decrease in bow lift bothers you enough to consider lowering it one hole again. Also a heavier load might be a consideration.

Sounds like you are pretty pleased - do you still feel the need to get the RPM's up? If you do you may have to change props.

Bob

 

[Esox]

Re: Prop Recommendation

So far I guess I'm pleased with the results. I really would prefer to turn the engine to 5500 @ WOT but I really don't want to drop to a 17" pitch prop. I think the Ballistic is a bad choice for this hull. When the engine was mounted at lower heights it felt like it had more lift. Every time I went up with the engine it seemed to reduce the amount of lift (does this seem right?). When I was out yesterday it was very noticeable. I think that is slowing it down a little as it feels like there is more wetted area now than than with the engine all the way down on the transom. At least that's the way it "feels" to me. Not sure what the next step is. I would like to test some props but I'm not sure what style of prop would work well for this setup. I haven't had the boat out in really rough water and I'm afraid that the Ballistic won't hold very well at these heights. I'm wondering if a 4 blade would work better in this case. I'm getting very bad ventilation on turns unless the engine is trimmed all the way in - which makes the bow plow and steering unpredictable - but it will still ventilate if I give it a little throttle in a turn even when trimmed all the way in. Hole shot is more than adequate and as long as you come out of the hole in a straight line it doesn't ventilate. I hope all this makes sense.

 

[Crownie2]

Re: Prop Recommendation

It is not unusual at all to have to trim in when going into a fairly sharp turn.

Yes add'l engine height can reduce the ability to lift the bow. A good bow lifting prop usually takes care of this. The resulting bow down position can often make carving turns more predictable - but perhaps not in your case.

IMO, I would not look at 4 blade props for your setup - find a better 3 blade if you must.

Good Luck

Bob

 

[Esox]

Re: Prop Recommendation

Thanks for the reply Bob.

I am looking for a dealer that will let me test some props out. I'm just not happy with the amount of ventilation that I'm getting with the current prop. Quite frankly, I was happier running the original AL prop with the engine all the way down on the transom. The ballistic cost me speed and rpm at lower engine heights compared to the AL. Now with the engine all the way up on the transom the speed and rpm is only slightly better than it was with the AL, only now it vents easily which is not a great tradeoff IMO.

From reading some other posts on here I'm looking at testing a Turbo 1 and a Stiletto Advantage. Are there any others that I should consider looking at? Thanks again.

 

[walleyehed]

Re: Prop Recommendation

This rig is close, in many ways to mine....
I Believe you will see real good results with a Turbo1 with the engine mounted directly to transom...I also think this boat will come alive with either a 19P Lightning or a 20P Raker. Believe it or not, this boat likes to run with the nose up and clean, and does very well with a Bow-lifting prop.
Email me at ktsander@st-tel.net
I know a dealer in your neck of the woods that would likely allow some test props.

 

[Esox]

Re: Prop Recommendation

I ran out of time last year to do any more testing. I had the boat out a couple weeks ago for the first time this season and all was well so it's time to work on the setup again. I don't think I can take too many more outings using the ballistic. The venting is driving me nuts!!

Kenny - Can I send you an email?

 

[Esox]

Re: Prop Recommendation

I ordered a Turbo 1 and it should be delivered today. I can't wait to get out and make some test runs with it. If it will lift the bow and reduce the wetted area I should see some better #'s. The ballistic just can't lift the bow at the current engine height.

 

[Esox]

Re: Prop Recommendation

Well I got the Turbo1 and got out yesterday for some testing. The conditions were not the same as I was testing in last year. It was very windy and the water was very rough. In order to get a good comparison I brought both the Ballistic and Turbo1 and ran them both. The results were surprising to say the least. Here are the best runs for both props:

14.5 x 19 Ballistic

5200 RPM
47.8 MPH


14.25 x 19 Turbo 1

5500 RPM
46.4 MPH


The feel of the boat is completely different with the two props. The T1 has a great hole shot and mid range acceleration. It also holds better in turns than the Ballistic. I can start trimming out as soon as it?s on plane and keep trimming until it reaches full trim. On one run the T1 lost bite at full trim and RPM went up a couple hundred and the speed fell off and I had to trim in a little to get it to hook back up. I must say the engine sounds a lot happier with the T1.

The hole shot and mid range acceleration with the Ballistic is not even close to the T1. I can?t start trimming as soon as with the T1 and I have to trim it up a little at a time to keep it hooked up. It does feel as though the Ballistic is lifting the bow a little more than the T1 but the T1 seems to provide more overall lift.

I guess what confuses me is the difference in slip between the two. My quest for more bow lift continues??.I?m thinking of lowering the engine and retesting both props again. Anybody have any suggestions?

Mike

 

[Esox]

Re: Prop Recommendation

Update: I called Precision Propeller today and they were very helpful. They want me to send the T1 back to them so they can check it out. They said there is something wrong and it should not be turning that many RPM's at that speed which I agree with. Once they get the prop back they are going to check it out and then they can make a suggestion. Nice to see some companies still stand behind their products.​

 

[rndn]

Re: Prop Recommendation

Great information in this thread.

 

[Esox]

Re: Prop Recommendation

Thank's rndn. I actually have a lot more data that I haven't added - kinda felt like I was posting the results to myself there for a while. When I get a chance I'll update this thread with the new data. Hopefully someone will find it useful.​