And THAT had a bad holeshot?

and they claimed it was only the equivalent of a 90 hp prop motor?

Jeeez, that's about a 50% power loss. That's RIDICULOUS.

I see they had 90, 120 and 175 hp versions of the sport jet. Are you sure this was a 175??????

That just doesn't sound right.

Kev

My boat was a 1995 Bass Tracker Pro 18 jet. In 1995 the only motor offered in that boat was a 90 HP Mercury Sport Jet.

In 2005 (I don't think the offer the jet anymore) they offered a 175 HP Mercury Sport Jet Standard.

The rest we will have to agree to disagree.

No, it's not a need to agree to disagree, but to understand better what we are talking about.


So here's the question (and this can be confusing because over the years different manufacturers represented it in different ways, and some, like Yamaha, even switched over the years).

What do you mean by 90 hp SportJet?

Sometimes when they call something a

90 hp Jet - it is because the POWERHEAD is rated at 90 hp (and that is what it would produce at the prop if so equipped). But because of the loss of efficiency it's actually only putting the thrust out of a 60 hp (I could see how this would cause some thrust and hole shot problems). In this case I'd expect the powerhead to be a V4.

OTHERTIMES they might still call it a

90 hp Jet - but mean that it is actually a larger powerhead (like a 130 hp powerhead) which would rate much higher with a prop (i.e. 130 hp). But since the thrust it puts out is only the equivalent of 90 hp, they still call it a 90 hp Jet. In this case I'd expect the powerhead to be a V6.

When it comes to a 200 or 250 OptiMax Sport Jet from Mercury we are talking about the RATED HP of the powerhead. Which is roughly the equivalent thrust of a 140 hp or 175 hp prop outboard (respectively). Both those powerheads are large V6s.

And many 18' bowriders, designed for outboards often max at 150 or 175 hp ratings, meaning that should be more than sufficient for holeshot (since the very same bowriders would likely be offered with smaller engines, like 115 hp, at lower prices).

Looking at that, I'd GUESS that your 90 hp Sport Jet, was a 90 hp powerhead (with only 60 hp of thrust), which led to your negative experience.

Kev

If you use any boat (that weights anything to get a fair ride) as a sport boat/fun toy the fuel burn will be higher than if you steady state cruised that boat/engine combo.

I think that the poor milage thing with lightweight jets is over-blown.

They are different, so take a ride and see if their strong points match up with your intended boating style.

Limited rain and wind protection makes a center console fishboat a "hard to work well choice" for me, but they do very well for the folks that need their particular strenghts to go boating---THEIR STYLE.

The "Mercury" Sport Jet 90 (and 120) use a Force power head. I believe it is an inline 3 cyl. I don't know the displacement or crankshaft rating of the power head, but they are pretty widely regarded as doggy, whether in Regal, Boston Whaler, Bayliner Jazz, Sugar Sand Mirage, or apparently the Bass Tracker as well.

The point is that the 2.5L Merc 175 hp and 3.0L Opti (both actually Merc V6s) are a much better set up, with a larger diameter impeller, 7.25".

# 820630R 6
Remanufactured Dressed Powerhead Complete with fuel and electrical system. Fits 1994 1/2 Force 90 Sport Jet w/ oil injection

I owned a Checkmate with the Merc Sportjet 120xr.

It was based off the Merc / Force 120 4 cyl, that traces is origin back to Chrysler. I put 7 seasons on it and never did any repairs. A fresh set of plugs each spring was the extent of my maintaince.

The 1994 - 1995 SJ 90 and 120s had a Stator issue that was fixed by 1996.

I think the concept that the jet are not effecient comes from how they are driven. The checkmate was not bad on gas when driven under normal conditions, but with a light hull, quick steering, excellent throttle response, you tend to drive with a lot more " driver input ", and the gas bill did go up quite a bit.

Glad you chimed in here Scott. One of the issues that is raised from time to time is low speed fit. To the effect that jets require relatively high rpms for low speed running. Or have difficulty holding a steady speed at low figures. What was your low speed experience with your Checkmate?

Kelly

Kelly,

My Checkmate was only 15 FT LOA, so overall I did not have a lot to handel.

I found the slow speed handeling to be very good. The boat was somewhat sensitive to weight distributtion, but we enjoyed many low speed cruises over the years.

I also noticed that people who had no time on a jet tended to oversteer at slow speeds, and were constantly making corrections followed by over corrections.

With time and a little direction from me, they would learn to use less sterring input, and get the wheel back to center sooner. This was very evident at displacement speeds, and I think adds alot to the notion that jets have poor slow speed handeling.

With no outdrive to give any rudder effect, I did learnd to use the throttle at slow speeds, mostly short bursts to keep the boat moving in the direction wanted. At very low speed, you could turn 360 degrees with the boat's length.

A jet's ability to be put in reverse at speed is very usefull in docking. In windy situtations, I could come in faster and at a sharper angle than I would if I had a prop, and then go to reverse, cut the wheel and in one motion pull the stern in to the dock and quickly stop.

In relaitve terms high speed handeling was excellent. As compared to my Chap and other sterndrive I have time on, there is a greater range in variablity in handeling.

With more thrust, comes better / quicker response to steering input, which just made you want to flogg it more. I always had my right hand on the trottle. The Checkmate had much more of knife point on the bow / keel than most and would quickly bow steer when off plane, so you quickly learned not to cut throttle all the way. I was constanly scaning and preapared to turn quickly, as opposed to try to come to a stop.

A few years back, John drove it on Lake George, he enjoyed putting it through its paces, and at one point was really cutting hard to port, and kept pushing the throttle. At a certain point the stern would break free and you would go in to a 180 spin, I could tell we were getting close, so I just held on and kept an eye on John. I was a lot of fun to see him realize the back was slipping . Or as he put it, he was sitting a couple of inches higer in the seat after the spin.

Thanks Scott, very good info

Kev M,
I'm sorry if I miss led you. I didn't have a negative experience with that boat. It did what I bought it for, which was to run shallow water. The river in front of my house is shallow with lots of rocks. They told me when I bought it that the HP rating was the out put. It would do around 38 in smooth water.

I own a 2004 Yamaha SX 230 and before you go bashing today's jet boats. You have to drive one.
Everyone who has ridden in my boat, who has experience with other boats cannot believe how nice Yamaha made their boats. The hole shot is the fastest of any boat in its class. Check any review, and they all say that is true. There are no sharp edges with these intakes. Clearing weeds is accessed from the top of the boat, via clean out plugs. So no swimming under the boat. Dual throttles allow for 0' turning radius. You can spin the boat right at the dock. Draft of the boat is 18" and less on plane. These motors are driven daily in the R1 Motorcycle and RX-1 Snowmobile and have a redline of 15K RPM. So a 10K Rpm is not even pushing these motors. Fuel efficiency is great and boat test.com has the exact figures. As for maintenance, Stern drives are much more labor intensive, due to so many more moving parts. Remember, these are 4 strokes, so longevity is not compared to the old 2 stroke motors. I do agree Top Speed is not equivelant to HP, but 0-49 MPH on GPS is about 7 seconds. Fast enough for me. I get a full weekend of towing and cruising on one tank. Boat test.com says 134 miles to a tank. Thats a little over 2 miles per gallon which I think is above average. 3.4 MPG at cruising speed.
I think they are like sports cars on the road. They handle very well and corner much better than a standard I/O. Slow speed is better than a inboard, but not as good as an I/O. If anyone ever wants a ride, up in NH. Let me know.
BQuick

Thanks for jumping in with the your real life experience. I think I would have gone with one if I could get a 23' boat in my garage.

waterlogged,
Just so you know, they just came out with a similar design in a 21'....Also, the trailer has a swing away tongue, making it fit in the garage a little better.

Yeah, I know...just after I bought my boat The dealer didn't even have any yet when I was looking. Plus, I never buy the first year a new model is released. Just have to wait awhile.

The Yamaha SX210 was just featured on BoattestTV on Saturday and their review, including video, can be found here:

http://www.boattest.com/boats/1042/overview.aspx

You may have to sign-up for an account w/ your email to see it. I have a free account and was able to access.

The mpg was impressive...about 4.1 @ 31 mph and 6500 rpms...aided by a much lower weight/length ratio I assume.

Yeah, I was surprised by the weight, aobut 2800# That's pretty light for a 21' boat.