TyBoo repower

[Wandering Sagebrush]

WOT at 5900 and 40 mph with the current, 37 mph against

What are the specs of the prop you are using?

I haven't yet been able to get above 5400 RPM with my Yammi 200.

I'm not sure it will translate between engines. Per Sportcraft, Suzukis are geared much lower than other engines..

 

[TyBoo]

The Suzukis seem to fish ok.

 

[TyBoo]

What are the specs of the prop you are using?

I haven't yet been able to get above 5400 RPM with my Yammi 200.

I am not sure of the prop diameter (16" I think) but the pitch is 20. The Suzuki gear ratio to the prop is lower than Yamaha, so the prop numbers would not be very close for the two motors.

 

[thataway]

You might try putting a little more on the trim tab. But if it is steering straight, it is probably close. As the HP has increased some have gone to "power assist" Sea Star steering. Definitely more torque with the bigger diameter and larger pitch prop--a price you pay for the hole shot and top end speeds.

 

[TyBoo]

Thanks, Bob. I am not going to be too concerned about it, the added effort isn't that much. It's just something I noticed. I will give the tab a little more angle in the direction it is already pointing and see if anything changes.

 

[TyBoo]

To alleviate the crowded kicker problem I found a spot in the rotation of the fully raised motor that lets the main motor clear it through all its turning and tilting motions. I bolted a piece of stainless flatbar bent just right to provide a spot to secure the tiller handle using velcro straps that holds the little motor in the one position that works. I can get a picture of it in a bit.

There is still a little awkwardness involved in using the kicker to run the boat, but since it won't see much use I think it will serve me well. Moving the kicker back and out to starboard (I have it on the right side) would create other hassles with running it anyway. Maybe a steering link rod is in my future, although one of the only two times I needed a back up motor was due to loss of steering.

We are going out now to welcome the E/V Nautilus back from their expedition off the Oregon coast.

 

[TyBoo]

What are the specs of the prop you are using?

I have it out of the water for the 20 hour service so I was able to get a look at the prop. It is a Suzuki branded 3x15x21R.

 

[TyBoo]

How was the handling at 40 mph?

The best answer to your question is probably squirrelly, with a little bit of rattly thrown in for sound effects.

Glass smooth water will be required for any WOT runs! The old girl rattles and chatters with every ripple at 40 mph. But 20 mph at 3500 and 30 at 4500 is nice to have!

 

[thataway]

The best answer to your question is probably squirrelly, with a little bit of rattly thrown in for sound effects.

Glass smooth water will be required for any WOT runs! The old girl rattles and chatters with every ripple at 40 mph. But 20 mph at 3500 and 30 at 4500 is nice to have!

About what I expected--not sure if she became airborne or not! The engine will last forever at 3500 to 4000 RPM!

 

[smckean (Tosca)]

I have it out of the water for the 20 hour service so I was able to get a look at the prop. It is a Suzuki branded 3x15x21R.

I don't know/understand much about the gearing of outboards, so I find this puzzling. With my Yamaha 200, I use a S4x14.65x15R, and can only reach 5400 RPM at WOT. I tried a S4x15.5x13R, but something was wrong and I got lots of vibration (Fred on Anita Marie uses this 13" pitch prop with results somewhat better than my S4x14.65x15R). When the Yamaha was first installed we used an old 17" pitch prop for its first sea trail. Got over 40 MPH at WOT but only 4800 RPM.

So 21" pitch seems so high to me, but I assume that's because of the difference in the gearing btwn the Yamaha and the Suzuki. Is anyone willing to explain this to me (briefly), or refer me to a link where I can educate myself?

 

[thataway]

I don't know/understand much about the gearing of outboards, so I find this puzzling. With my Yamaha 200, I use a S4x14.65x15R, and can only reach 5400 RPM at WOT. I tried a S4x15.5x13R, but something was wrong and I got lots of vibration (Fred on Anita Marie uses this 13" pitch prop with results somewhat better than my S4x14.65x15R). When the Yamaha was first installed we used an old 17" pitch prop for its first sea trail. Got over 40 MPH at WOT but only 4800 RPM.

So 21" pitch seems so high to me, but I assume that's because of the difference in the gearing btwn the Yamaha and the Suzuki. Is anyone willing to explain this to me (briefly), or refer me to a link where I can educate myself?

It may not be quite a simple as it seems: The Yamaha 200 thru 2012 had a gear ratio of 2.0:1 After that they were 1.86:1 (according to tables I have reviewed)

The most recent Suzuki 200, has two gear step downs--one between the crank shaft and drive shaft and one in the gear box total gear ration is 2:50:1 from the current web site. Another table shows it to be 2:29:1 for some older motors.

in any case, the Suzuki is turning slower than the Yamaha at the crank shaft, so it swings a prop which has more pitch.

There are many factors which contribute to RPM at WOT including proper setting of the outboard below the bottom of the boat (amazing how many are off), the # of blades, the cup of the prop, and to some degree the rake of the prop.

Rake:



Cup:




Gear ratios on the outboards can range from about 1.40 to 2.70, depends on the brand, the HP, and year.

It is possible that in your case there is some vibration being set up because of the large diameter of the other prop you tried.. You are close with the 5400 RPM--
Running a quick check on one of the prop sites, I see that all of the 4 blades for your motor (assuming newer than 2010) are no more than 15" diameter. You should be close with the 14.65 diameter. Maybe up or down, some trim adjustment? But I would not complain at 5400 RPM--within specs.