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Discussion Starter · #1 ·
Need some ideas. I just repowered my 2010 bay boat with a DF175 Suzuki. She plains at around 3200 rpms. With motor tilited down and trimtabs barely applied when I have to make a tight turn I lose speed and sounds like the prop os losing its bite. Currently have a 16x20 prop tghat gives me 5900 rpms at WOT. I run thje white oak and have to have the turn capabilities since it is a winding path to get from Stella to the Swansboro bridge. Any ideas out there?
 

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If you can try a 4-blade prop that may make the difference. Not sure what size or pitch you'll need to get you to that 5900-6000 RPMs you need for WOT but there are some converters out there that can help you get close. Are you trimming down the motor as you are turning?
 

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4 blade prop, cupped prop, trim down slightly. Where is your A/V plate running when on plane? A hydrofoil may help keep some water on the prop.

All of that said, if you are trying to run your boat as skinny as it will go, you will just have to deal with blowout in sharp turns, it is a byproduct of running the prop so skinny. The 4 blade with more cup to it will be the only solution if you dont want to trim your motor down anymore. you could also drop the motor a peg or two and adjust the trim tabs until you have it how you like it.
 

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To me it doesn't sound like a prop problem but an outboard height problem. First question (may seem dumb) Is the new outboard have the same shaft length (25" old- 25" new) as the old?
second question: do you know how far the old outboard extended below the lowest point of the hull.? if so check that measurement on the new outboard it should be the same distance.
Just because the old one was mounted say in the third mounting hole and the new one is too doesn't mean it is at the right distance below the hull.
If all of the above checks out to be the same then I'd look at the prop. Would hate to spend $400 for a new prop when I could have lowered the outboard one hole and solved the problem.
 

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Discussion Starter · #5 ·
Boat engine appears to be set up same. They are both 25 shafts and same make. Old engine was a 115 suzuki 4 stroke. As for lowering the engine I can only trim almost half way up now if I lower it no trim room at all. I have hyd steering. This motor appears to be maybe a bit higher looking at old pics. Maybe a inch max. I think the old motor was flush and this one is about 1/2 to 1 inch higher. Was wondering if i could have the prop I have now cupped over at Bobs Prop shop. Don't even know if that is possible with SS props.
 

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Bout time hit it on the head. if thats not it Id try a good hyrofoil that turns down on the ends as they push more ater inward around the prop, then if all else fails start prop shopping. I really dont think its the prop.. What brand of bay is it? Different hull styles have their own personalities/quirks
 

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A 4 blade pro will hold MUCH better in turns & let you trim your motor up higher for better fuel economy..

Hydrofoil will make you fish tail @ low speed ...
 

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Discussion Starter · #8 ·
well i have tinkered with this till i am silly and broke. I have just decided to trim it down going into turns and then trim up when i pull out of them.
 

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When running through turns you should always trim down anyways, for the better "traction." This is much more important in bass boats persay than a bay boat but I still had to trim mine down on my sea pro(I was running almost 60 mph gps so she was gettin it anyways). Do you have a hydraulic jack plate? That is a bay boats best friend...it gives you some offset from your transom and also lets you make minute changes while you are running for better fuel economy and engine performance and boat handling. The single best investment for a bay boat is a toss up between a power pole and a hydraulic jackplate. The cost is about the same, But I have to say the jackplate is more important. It also helps in skinny water, I could get into 13-14 inches of water EASILY in my 21' 6" bay boat loaded with fuel and equipment and 2-3 people and not worry about killing my motor. I could raise it up on the jackplate and put the propshaft about 4 inches above the bottom of the hull. Running the boat is a whole other ballgame too. If you cavitate, lower your jackplate by simply bumping the button, and that 1/4-1/2" makes all the difference in the world. Performance gains with boats are measured by 1/4" when it comes to any motor adjustments. Bob's Hydraulic Jackplate is a popular model.
 

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Discussion Starter · #10 ·
No no jackplate yet. having a hard time separating myself for that much cash. I have just learned to lower my tilt when going into a turn. seems to work fine when i remember it lol.
 
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