Props for Marlin

Papo

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Hi everyone,I repowered my Marlin with 300 Suzuki twins.I had 3x16x18.5 it was slipping a lot to plane it.So a friend gave me to try out 3x16x20 the slipping was a little less but couldn’t top end it cause of the poor conditions.Been thinking to go 4 blades or try eco enertia 3x 16x19 .Im open to all suggestions and help will be very appreciated.
 

Harpoon

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I'd connect with propgods. I suspect ur over pitched.
 

Island Pilot

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I'd connect with propgods. I suspect ur over pitched.
Hi everyone,I repowered my Marlin with 300 Suzuki twins.I had 3x16x18.5 it was slipping a lot to plane it.So a friend gave me to try out 3x16x20 the slipping was a little less but couldn’t top end it cause of the poor conditions.Been thinking to go 4 blades or try eco enertia 3x 16x19 .Im open to all suggestions and help will be very appreciated.
Did you figure the props out? I am interested in your performance with the duke 300s.
 

Blempa47

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we are running the 3/16/18.5's.... ive found that you have to use the tilt trim and start with them all the way down to get the best grip with the holeshot... then trim up depending on conditions once on plane.... our engines are mounted ont he 2nd hole hole pattern from the top....
 

Mindskew

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Thanks for that info. I have engines arriving some time this week and need to order props today.
 

Fido

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To add to the above we are running twin 300 Suzukis on a Marlin 300. We have Suzuki 3/16/18.5 props pulling 5500RPM at 39 knots. We will be trying 17’s in an effort to pull more RPM.

At the moment there is zero slip either coming on plane or in a high speed turn.
 
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Fido

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Hi all,

I have some further figures re Marlin 300 with twin Suzuki 300’s.

We have raised our engines one hole and are now pulling 5800-5900 RPM at 40-41 knots. Fuel burn was around 185 litres per hour.

Cruise at 4000rpm was 26-27 knots at 72-73 litres per hour.

We have full side curtains riggers, centre rigger, radar etc. Fuel would have been 75% and 50% water.

Propellors are Suzuki 3/16/18.5

Performance has not been compromised by raising engines. Trim down to get on plane as usual but can go hard over at 4500-5000 rpm and 30 knots with zero slip.
 

Kizuna

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Hi, I've been on Grady's most of my life but I'm new to the forum.

Not to hijack the thread, but I just repowered with 300 Suzuki's and the boat gets unstable and lists back and forth when it catches certain waves or wake from another boat. This is small wake from 18-20 foot boats, and it happens at any speed with the boat on plane. It also happens with light and heavy loads. The boat didn't behave like this when I had 225's

I'm running the same 3/16/8.5 props, and the engine's are mounted in the second hole from the top where the cavitation plate is flush with the hull bottom. I have no slip, but always trim down when taking off and then trim up as the boat begins to plane.

Fido, regarding raising the engine one hole, is it now in the 3rd from the top?
 

Mindskew

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I was seeing something similar and made a couple adjustments that helped a lot. First, I had started with a toe-in position of 1/2”. This means the front of the lower, measured from the pointy part, was 1/2” farther apart than the center of the prop shaft. This had me finding myself actively working to keep the boat in a straight line. I made adjustments to bring the pointy part together until the wake converged farther back and this solved that issue. Next, I was finding that certain trim settings was causing the boat to “walk” when waves were hitting the chine. Trimming the engines up or down solved that nicely.
 

Kizuna

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Thanks Mindskew, I was wondering if it was a toe alignment issue based on another thread I read. The thing is the boat rides perfectly fine and easy to keep on a straight line in flat water.

On plane I'm running the trim up ~30%. Do you think the bow is riding too high and having too much of the chines out of the water? Then when waves catch more of them it throws the balance off. It does seem like a chine walk but it's happened to me going only 16-18 knots.
 

seasick

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I was seeing something similar and made a couple adjustments that helped a lot. First, I had started with a toe-in position of 1/2”. This means the front of the lower, measured from the pointy part, was 1/2” farther apart than the center of the prop shaft. This had me finding myself actively working to keep the boat in a straight line. I made adjustments to bring the pointy part together until the wake converged farther back and this solved that issue. Next, I was finding that certain trim settings was causing the boat to “walk” when waves were hitting the chine. Trimming the engines up or down solved that nicely.
By saying that you made adjustments to bring the pointy parts together, I take it you had to decrease the toe in. That would move the convergence of the wakes farther back from the boat. When you got a decent setting, did you measure it and if I may ask, what is your motor spacing, center to center?
 

Fido

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Hi. Yes engines now mounted 3rd hole from the top.
 

Kizuna

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Hi. Yes engines now mounted 3rd hole from the top.
Did you run the boat on the second hole and then raise it? Are you experiencing and cavitation on hard turns and the boat leans? If you went from 2 to 3 how much trim did you lose? And most importantly did you notice a difference in how the boat handles?

Sorry for all the questions, but I'm trying to figure out how to get the boat dialed in, and right now it isn't handling as I know it should. My sister as a passenger at the back of the boat said it feels like the boat is skidding around, like when your riding a tube being pulled by a boat.

My hope is by raising the engines one hole, the hull will ride deeper in the water and create more stability. Between my father and I, we've owned a 20' Overnighter, a 25' Sailfish, 268 Islander and now my 300 Marlin. I'm familiar with the SeeVee hull and how Grady's handle overall. Since the repower she isn't the same.
 

Exocet

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Old thread but did you figure this out? I had a similar experience with my 232 and twin Yamaha 150's. I resolved it by raising the motors. I recently repowered my boat with twin Suzuki 200's and had no issues as the company that sold and installed the engines dialed the height before giving the boat back to me.
 

usmm1234

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I solved the slippage problem with PowerTech 4 blade props for my Suzuki 250’s on my 330 Express. Awesome! The Suzuki Props are junk. They are made by Solas and they are soft and flexible. I tried 2 different sets With no luck. The other benefit is how well the boat maneuvers around the marina at low speed. The 4 big blades give incredible control. They will also keep the boat on plane at lower speeds.
The guys at PowerTech will walk you thru it on the phone. You need to run the boat wide open and get RPM and top speed. They also need the diameter and pitch of your props now.
PS: I forgot to mention. I can now ram the throttles forward and not cavitate at all. The boat jumps on plane. I max out at 6100 rpm. If I trim past 20% At WOT, I hit the rev limiter. With this big heavy boat. I like this set up. If it were a bay boat, I would move to a higher pitch for a higher top speed.
Ive attached a picture of my fuel/speed performance. That is with full fuel and water. That’s the best numbers I have ever heard of on a 330. The Suzuki guys are the ones that referred me to PowerTech when I was having problems with cavitation.
 

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Exocet

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Thanks for the reply and glad you got it sorted! My Suzuki's came with new stainless props but I know the shop that installed the motors had to test a few different pitch props to get it dialed properly. I hope you enjoy the new engines! I am loving fly by wire controls such a huge difference over my cable controlled Yamaha's.