Sportsman 180 Speed and Handling Questions

[ctay]

Used 180 Sportsman
Yamaha 4 stroke 150HP
Powertech 13.25x19 SS prop
Standard Cable Steering

Been out five times, 4 lake 1 sound/ocean, and noticed the following, hoping someone can give some pointers:

1) Throttle noisy (clunk) to engage and inconsistent - it's almost 50/50 whether it revs steady or jerks into a higher rpm and catches everyone by surprise, almost like it skips over lower throttle and decides to jack rabbit forward.

2) Lower RPMs - 1500-2000 RPMs, the bow rises significantly and the boat struggles greatly to move forward. More throttle to around 2800-3100 RPMs would SLOWLY plane the boat and move it forward quickly to around 3500-3700 RPMs.

3) Also, at lower RPMs, under 2000RPMs, such as slow wake zones and approaching ramps, Steering is all over the place. Holding the steering wheel straight, the boat would move in a lazy S or snake formation. Seems to have lots of play in the wheel. Somewhat hard to maintain handling in narrow spaces such as slips and smaller docks. Need to constantly steer left and right to keep straight.

4) At higher or near max RPMs, Steering is VERY hard to turn left and very easy right. In fact, if the boat is above 3000 RPMs or so, and I briefly let go of the wheel, it will within milliseconds spin quickly sending to boat violently to the right. Good thing everyone was holding on to something!

5) Max speed doesn't seem right. Currently maxing at 5200-5300 RPMs and 33 knots (per GPS). I've read the Grady 180 and Yamaha 150 should do about 5800-6000 RPMs and around 45 or so knots, maybe more.

Some of these issues I've read can be reduced, perhaps eliminated by changing prop to a 17 pitch, raising engine a notch on transom (currently on 2nd from bottom), adding trim tabs and/or adjusting trim tab fin on lower unit. I've adjusted the fin, which was set one notch to port, back to middle, but haven't noticed in difference in steering. I usually trim the engine in to around 2-3 on the gauge, but haven't seen much improvement in speed. Setting it low does help to plane the boat out faster, of course, but it still takes forever and the engine struggles badly.

Currently considering SmartTabs and changing to a 17 pitch prop, both for faster planing and more speed. Not sure what to consider with the steering or throttle. Any thoughts or tips about any of the issues would be greatly appreciated!

 

[Parthery]

1. Sounds like your cables have some free play in them. When they are adjusted properly, everything should engage smoothly and be smooth throughout the entire range.

2-5. All related. First, it sounds like the motor is trimmed all the way down. Don't be afraid to trim it up slightly. Trimming it out reduces the wetted surface in the water, which reduces drag, and torque steer. If your trim gauge works, trim up to the 2nd bar and the right hand torque will be reduced. As far as the side to side steering at idle speeds, this is characteristic of the deep v hull.

You might need to look at a different prop. At full throttle, you should be in the neighborhood of 5800-6000 rpm. Even trimming it out, I don't think you gain 500-700 rpm. GW shipped your setup with the stock 13.25x17 SS Yamaha Prop. The 2 stroke 150s have a max rpm of 5500. On my setup, I'm running a 15.25x17 Merc Mirage Prop, and I can hit 5400 RPM and about 46 mph when I trim it all the way out.

 

[Greatty]

What Parthery said. Regarding #3, I remember my first test ride and thinking the same thing. I quickly got used to it. Good luck with your setup, its a great boat. - Bob

 

[ctay]

First ride out, yes I had the motor trimmed all the way down. Other rides I tend to have it set around 2 or 3 according to the trim gauge. Doesn't appear to make a difference, perhaps 100 RPM gain. Hard steering left and quick steering right is also the same no matter the trim, maybe a tad less. I've had it as high as 5, but it is least efficient there. I likely need to change the prop to a 17 pitch for my 4 stroke 150. Now is your 15.25x17 Merc Mirage Prop running on a 2 or 4 stroke, or does it really matter? Just wondering if I should go back to stock Yamaha prop, which I do not have in my possession or try another 17 pitch prop of larger diameter, such as your Merc or maybe another Powertech.

In regards to the steering play, yes I've gotten used to most of the play, just a bit annoying at slow speeds. Oddly, I've watched other deep v hull type boats other than Gradys at slow speeds and did not notice much boat drift or the driver adjusting the wheel. Perhaps a product of cable versus hydraulic steering?

Other than my concerns about speed and handling, the boat has been great!

Thanks for the replies ...

 

[Parthery]

I'd try to get my hands on both a 17M and 19M Yamaha Prop and run them both and see what you get. I don't know a lot about Powertech props, but your RPMS are definitely low.

My 180 has a 150 Saltwater Series (2 stroke)....I've run a 180 with a 150 4 stroke and RPM at WOT was 5900. Top speed by the GPS was 47-48 mph. Additional weight, gear, bottom paint, etc... will slow you down some, but you are aways off.

A good dealer can help with testing props...just keep in mind that if you hit something or damage it, you've probably bought it. The other option is always EBay...buy one..try it...if it doesn't work, take it off and sell it.

 

[ctay]

Thanks, that's pretty sound advice. To you or anyone lurking this thread, is there much difference in performance of diameter size between different 17 pitch props, such as 13 thru 17 inch, Aluminum versus Stainless or 3 or 4 blades? Boat is mostly lake use with some ocean within 2-5 nautical miles. I don't risk more than 3-4ft. seas in this boat. Last weekend right after Earl was a bit interesting. Can't say I enjoy 6-7 ft swells slamming the boat. :shock:

 

[bayrat]

Wandering at slow speeds IS an issue with deep v hulls. You'll soon get used to just compensating for that and it will become automatic. As far as the trim tab on your lower unit, you have to adjust it in the direction that the boat pulls in or steers more easily in, which in your case is to starboard. Move the trailing edge from straight back to 1 notch to starboard(should be marked). Otherwise figure about 10-15%. Try that. Should be an improvement..good luck..john

 

[ctay]

The trim was originally set to one notch to port. After two outings I moved it over one to neutral. Didn't seem to make a difference. I'll try one more notch to starboard and see what happens. Thanks!