Prop Pitch Recommendations/ideas Please

[VitaBene]

Originally Posted by AC2717

I have read that that lower-horsepower engines can bog down if fitted with an outboard propeller with too high a pitch and diameter, and that can wear heavily on internal engine parts.

Just like a car and gears. Too much prop and it will bog, not enough and it will over-rev. The key is finding the sweet spot. A lot on marinas have used props that they may let you try.

[AC2717]

Originally Posted by VitaBene

Just like a car and gears. Too much prop and it will bog, not enough and it will over-rev. The key is finding the sweet spot. A lot on marinas have used props that they may let you try.

thank you I will make some calls, I'm ok with the hole shot not being spectacular but speed and getting the hull out of the water is more what I am looking for at this point. again I do have a foil on the motor.

[Cal Coon]

I think you're just asking too much out of that motor for that much weight. I would consider more power.

[Dave R]

If it's not planing cleanly and seems to be straining, you need less pitch. Try an 8" pitch. The 10" pitch SS prop you have will not help at all.

[AC2717]

The experiments will begin Friday lol. In having looked at the motor placement further through suggestions, the anti- ventilation plate seems to be 2 inches or so under the keel line of the boat, which is a big no no. Old owner i know took the motor off at one point and probably installed it too low.

So step one is to move the engine up, which I have room on the bracket to adjust. Then I will by doing runs with the props to see performance results. with a tach tester.

[MAXUM]

With a boat that small it's not so much the prop pitch as it is the weight distribution. As you describe just shifting your self a couple or more feet forward makes a huge difference in how well the boat gets up on plane. If you have all the weight in the back of the boat already you are at a big disadvantage as you're asking a lot of the motor to have the power to push that up on plane with nothing to push the front down. I do not think that a different pitched prop will help much as you may hope it does. Those foils you put on the motor never seem to do much if anything at all. Ultimately you need to get more weight in the nose of the boat or get more motor. Just my thoughts.

I had a 14 foot boat (side console) with a 30HP on the back. It performed well with up to three adults in the boat BUT me as the driver was sitting mid way up the boat, passenger #1 seat was to the left and slightly forward of the captains seat, third adult was fine on the back seat. I did pitch down but that did not make a huge difference, some but not huge.

[AC2717]

the console is midship which is good. I'm hoping just picking the motor up as it is being dragged down by the water going above the anti-vent plate will start the change. Has to be a reason why Merc, Lowe and all the prop website are saying 10/11 pitch sizes mostly

the boat can only go up to a 30hp motor and the boat is rated for 5 people or 550lbs ontop of the 601 lbs the hull is. With that in mind i do not see 25hp being underrated for this boat, and I know the motor is running the way it should.

let's see what happens

[MAXUM]

Originally Posted by AC2717

the console is midship which is good. I'm hoping just picking the motor up as it is being dragged down by the water going above the anti-vent plate will start the change. Has to be a reason why Merc, Lowe and all the prop website are saying 10/11 pitch sizes mostly

the boat can only go up to a 30hp motor and the boat is rated for 5 people or 550lbs ontop of the 601 lbs the hull is. With that in mind i do not see 25hp being underrated for this boat, and I know the motor is running the way it should.

let's see what happens

I'd take that plate off and see what difference that makes. One thing you want to be careful of is not to raise that motor to much and cause a cavitation problem once you're up on plane.

I don't have my 14 footer anymore but I seem to recall I put an 11 pitch on it which was as low as I could go for that motor. That replaced the 13 pitch that was on it.

Ya know you might want to try a 4 blade spitfire prop on that motor if they make one. Gives a ton more bite and helps with the hole shot for sure.

If you can't really go with a bigger motor than I would assume that your package is optimized as best as it can be and agree it should be sufficient to handle what is on the recommended person\weight plate.

[AC2717]

Originally Posted by MAXUM

I'd take that plate off and see what difference that makes. One thing you want to be careful of is not to raise that motor to much and cause a cavitation problem once you're up on plane.

I don't have my 14 footer anymore but I seem to recall I put an 11 pitch on it which was as low as I could go for that motor. That replaced the 13 pitch that was on it.

Ya know you might want to try a 4 blade spitfire prop on that motor if they make one. Gives a ton more bite and helps with the hole shot for sure.

If you can't really go with a bigger motor than I would assume that your package is optimized as best as it can be and agree it should be sufficient to handle what is on the recommended person\weight plate.

Once I move the motor up, I am going test out a stainless 11 pitch I have and I also have a spitfire 4 blade with an 11 pitch that was supposed on there before I did the lower end over from the old owner. It is a little beat up so I did not want to put it on, but i am going to use it in the test runs, as well as the current 9 on there now

[MAXUM]

Originally Posted by AC2717

Once I move the motor up, I am going test out a stainless 11 pitch I have and I also have a spitfire 4 blade with an 11 pitch that was supposed on there before I did the lower end over from the old owner. It is a little beat up so I did not want to put it on, but i am going to use it in the test runs, as well as the current 9 on there now

Good luck, nice thing is you have some options to test.

[AC2717]

anyone have any 3M 4200 lying around? wanted to seal around the bolts once finalized for location (5200 is permanent). buying a $20-25 tube to use about 1/20th of it seems crazy to me

[8gv]

Amazon has it cheaper...


3M Marine Adhesive Sealant Fast Cure 4200 (05260) – Semi-Permanent Flexible Adhesive Sealant for Boats and Marine Applications – White – 3 Ounces

https://www.amazon.com/dp/B0000AY6B0..._ABDXEbQX311W5

[Dave R]

I doubt raising the engine is going to make a big difference. Adjustments to the X dimension are more of a top speed fix than a "getting it to plane" fix, but you should get that adjusted properly regardless. I hope I'm wrong about it not helping much.

[AC2717]

Originally Posted by Dave R

I doubt raising the engine is going to make a big difference. Adjustments to the X dimension are more of a top speed fix than a "getting it to plane" fix, but you should get that adjusted properly regardless. I hope I'm wrong about it not helping much.

in speaking to 2 different prop companies I have been told allowing water over the top of the anti vent plate from the back of the boat actually pushes down on the motor and prop and creates a very large drag situation. Fixing this they said will/should be a drastic change, again they said lol

right now the anti vent plate is below the keel while just sitting in the water and no added weight to the boat nor underway, then when getting on it and underway I am just dropping it lower under the water line.

hoping they are right

[ishoot308]

Originally Posted by AC2717

in speaking to 2 different prop companies I have been told allowing water over the top of the anti vent plate from the back of the boat actually pushes down on the motor and prop and creates a very large drag situation. Fixing this they said will/should be a drastic change, again they said lol

right now the anti vent plate is below the keel while just sitting in the water and no added weight to the boat nor underway, then when getting on it and underway I am just dropping it lower under the water line.

hoping they are right

At WOT and when boat is up on plane, you should be able to see the anti vent plate right on top or just into the water spray. If you cant see it you need to raise the motor which will create a lot less drag.

I think your on the right track...

Good Luck!

Dan

[AC2717]

Update:
Well upon measuring the motor was 3 inches give or take below where it should have been. I moved it up ad far as I could and still could go a touch higher but need to get it out of the water to do so. Got it up almost two inches. Significant difference and it ran better with the 9 pitch than the two different 11s, speeds into low 20s and easy plane. I am going to get a 8 and run a test from there

[AC2717]

Originally Posted by 8gv

Amazon has it cheaper...


3M Marine Adhesive Sealant Fast Cure 4200 (05260) – Semi-Permanent Flexible Adhesive Sealant for Boats and Marine Applications – White – 3 Ounces

https://www.amazon.com/dp/B0000AY6B0..._ABDXEbQX311W5

Fully agree but wont get by tomorrow unfortunately, even when i looked yesterday or Tuesday.

Now just realized that needs up to 24 hours to cure, looking for a faster cure product now