View Full Version : Merc vs Rotax

03-17-08, 03:52 PM
I've read most of this forum but didn't come across this dilemma

I've heard that Rotax is more dependable and easier to work on, so it seems a better choice, but what about performance...?
I'm expecting that my two rotax engines (220 hp total) should give a stronger feeling then a single 240hp Merc engine, am I wrong?

but then there's this guy on eBay sold his boat and kinda bragging about his Mercury equipped boat being better... :confused:
http://cgi.ebay.com/ebaymotors/SeaDoo-Speedster-Nice-Adult-owned-NO-RESERVE_W0QQcmdZViewItemQQcategoryZ80653QQihZ018QQ itemZ280207063879QQrdZ1QQsspagenameZWDVW

It'd be nice to hear from someone who knows for sure...

03-17-08, 04:45 PM
Thats a good question Stefan.....but the easiest way to answer this question is with a question. Which motor is heavest? If both are 240 hp, then it boils down to weight.
The 210 and 240 hp Mercury is a good engine. At the time it was used in the Sea-Doo's, it was one of the best and most powerful engines. Then the 4-TEC came along.
The Merc's 2nd attempt at an economical and powerful jet motor was a huge success when it first appeared in the first model of the Islandia, in 2000. Then, the 2000, the 787cc in the 1800 Challenger was changed out with the more powerful 210 hp Mercury. It was also used for a couple years in the Utopia. They were used in these boats until their last year in 2004, when the 4-TEC engine replaced them.
When you look at a sensible reason on why they were replaced, it wasn't due to performance, it was mostly to economy. If you have the same boat, with the same horsepower, but weighs a couple hundred pounds less, you get better fuel efficiency and performance. The Mercury a V-6, the 4-TEC a 3 cylinder. Half the engine, same (and more) horsepower.
So you see, it isn't that the Mercury was a bad motor, it was just that technology caught up to it. There are about 5 members here who use this motor and from there experience, has been almost maintenance free.

03-17-08, 05:21 PM
OK, I agree with the weight issue, so one Merc engine is lighter then the two 787 by rotax, but isn't it better to be pushed forward by two jets of compatible HP than by one. I just can imagine that one engine, even with an extra 20 HP would give a better start than those two rotax. I am sure it would catch up when gets to plane speed, but from the standing point... ? It's like having a better torque or something like that. It would be interesting to see the race of the 1999 and 2000 Speedsters

oh, remember now, I think the guy at the Seadoo dealership, when I was there a year ago, in Long Beach, CA mentioned that it was an experiment when Seadoo went from rotax to Mercury engines in 2000, and they didn't like it, so they gladly moved back to rotax with 4-TEC in 2005 or so

03-17-08, 05:46 PM
I think you mis-understood what I said....and the dealer who made the comment about the Mercury M-2 was way out of line. Sea-Doo enjoyed the relationship with Mercury. Sea-Doo used the Mercury engine once before, when they was building their first Sea-Doo's. I believe the Ski-Doo line of snowmobiles came out before the boats, but I know that Mercury and Sea-Doo have had a healthy relationship. You can read a thread I did about the history of Rotax and BRP and see, that Rotax and Sea-Doo's relationship formed, after Sea-Doo. Sea-Doo didn't always use the Rotax engine. So that dealer was talking out of his as*, in my opinion. Let me see if I can drop a link to that thread.......http://www.seadooforum.com/showthread.php?t=1838
But where I went wrong in talking about the difference in these two engines, was the twin engine Challenger. When I did the research, the sites I visited and the engine specs, were all based on one engine. It was my fault for not making some comparison to the twin 1800 Challenger.
The twin 1800 Challenger would perform like you said. It would jump off the line and hold its own against the 210 hp Mercury pretty good. I don't know when or at what time the 240 EFI was used, didn't think it was necessary to go that far into detail.
In my opinion, your almost comparing apples to oranges in this type scenerio. It's like racing a built Mustang or Camaro V-8 against a built Mazda or Nissan. The smaller engine is going to jump off the line, simply cause of it's weight and horsepower.....but in the long stretch, the higher rpm engine will become less efficient in keeping up the speed. The bigger engine has the endurance, the smaller end will have the hole shot and short distance sprint.......let me go see if I can find this link for you.
If I may point out one more thing. The M-2 served it's purpose and served it well. There are members here who still love this engine. Comparisons are done and debates are fun, but as a family, we don't knock around other peoples choice drives.........if you know what I mean.

03-18-08, 04:26 AM
I do know what you mean... please no offense to Merc engine owners :cheers:
Like you said, everyone is free to make a choice of the craft for himself, considering the engine type and it's pluses. The simple fact that a single Merc engine would not force you to buy a double set of spare parts and having to do the same job on the second jet when you do the maintenance or repair is good enough reason to go for it, especially with an older boat. Plus, the fuel economy should be better with one jet, even though it's a more powerful one.
I made my choice in favor of a double jet boat hopeing for a better juice at least at the start and a little piece of mind should something happen to one engine I would have another to get to the dock.

Another plus for those guys the Merc engine Speedsters are later models, 2000 - 2004, but I had to go for the 1998 with obvious wear and tear of that year, but it was my choice... (well, of cause it was a little cheaper :hurray:)

Now the question for me is whether to keep saving for a newer 4-TEC engine Speedster of 2005 or later, or should I get a good offer for my 1998 model go ahead and buy a slitely newer but still a two-stroke engine Speedster of 2000- 2004 , with Merc engine, that's why I started this thread

P.s: thanks for link on history, I've already read before and think it's very interesting, since I am new to boating everything related is enteresting.

03-18-08, 07:02 AM
If I had it to do all over again, I'd probably elect to buy the twin engine boat. Only because, last year, I lost my wearing ring and had to be towed back to the pier. Had I had a second engine, I could have done this under my own power.
Remember, if you find yourself in a situation where you lose an engine, you need to pinch off the water inlet to the dragging engine or your water flood it and could sustain damage!..........:cheers: