40+ vs. Century +

[Jerry In Maine]

Got my Century Plus off the bench and into the water today for the first time. This is the first Century I've owned so I didn't know what to expect...

My 40+ will push my boat with my wife and aboard at a screaming 5.1 mph max (according to my GPS), and I was a bit puzzled when the Century + managed the same speed and no more. I didn't exactly expect to be able to ski behind the Century, but I did expect a bit more speed than the 40+. The Century would indeed get me to max speed quicker than the 40+ though .

For what its worth my hull isn't the displacement style - i know the 'speed limit' that displacement hull have.

The motor did sound like it wasn't getting to full power - but again I've never run a Century before - for all I know it might have been running fine. Lots of smoke compared to the 40+ though (16:1 mix in both).

Any tips, ideas or suggestions?

[Hugz]

I thought all hulls were displacement until they reach a plane??

Love this add....

[Jerry In Maine]

I thought all hulls were displacement until they reach a plane??

Love this add....

yea, i believe you're right. i guess i found the hull speed for my 12 footer. wasn't sure that the 40+ was pushing me at hull speed but looks like the Century's similar performance confirms that it was.

thanks for attaching that add.

[fortyplus]

You will always have this "problem" when you cannot get a boat onto the plane and so the difference in top speed will be negligible with the larger motor although as you say the acceleration will be quicker. I think the slow turning prop on a Seagull also is a factor in limiting the speed achievable in any application and affects the possibility of getting a light boat on the plane with a Seagull motor. I think you start to reach a speed where the prop design doesn't really want to push you any quicker. I've seen little boats plane with 3-4 hp motors and one occupant, never with any Seagull (except in a video of a Seagull race). The shape and design of the leg, gear housing, skeg etc. are all not conducive to "high" speed. I noticed with my 90 on my 11' inflatable that as I increased throttle openings up to a point I could feel the extra push, then you reach a point where the noise increases, the revs go up, but I didn't feel any extra surge. It would certainly drive me beyond displacement speed, but then seemed to hit a "brick wall". I will have to take it out on one of the local lakes with a Forty+ to see how much extra benefit the 90 really gives.

However speed is not what they were designed for, when I use my 90 model on my heavy 21 foot boat it pushes that much faster than my Forty Plus's will so in the appropriate application you can certainly benefit from the bigger motor.

I guess if your Century is not reaching full revs, this might reduce it's ability to push you beyond displacement speed, perhaps the extra smoke etc. is a sign you are running a little rich, this will affect the ability of a 2 stroke motor to reach the higher revs you will need to exceed your displacement speed.

[Jerry In Maine]

i wasn't expecting or even wanting to plane, the 'gulls slow speed is fine with me for the putt-putt type boating my wife and I do on the small lakes, just didn't realize that the 40+ already had me at max speed - although if i had done the math for a displacement hull i would have figured it out.

i figure the Century's additional power would be an advatage if i was boating on water that was going uphill - but as long as i'm on flat water the 40+ will be my first choice to toss into the jeep when i'm heading out, but I do want to get the Century running right. Smokes like crazy although bore and rings were in good shape...

to lean the carb I'd turn the needle adjust screw inward a turn or two - correct?

[fortyplus]

Yes if you push the needle down you get less fuel and more air because the slide is open further, letting more air in relative to the needle height. I would check your float height and function first before adjusting anything else on the carb, if the fuel level in the carb is too high, this will give an over rich mixture. IMO adjusting the needle height is more of a fine adjustment, and while it may improve things, it's probably not the root cause if your mixture really is that rich.

Also I presume the motor was set to run on a 10:1 mix originally, if you are using 16:1 this will make it run richer because your fuel mix will be thinner (less viscous) than intended. The reduced oil could also affect the running of the motor if insufficient to seal the bearings etc.

The extra push of the bigger motor can be handy in strong winds and rough water, which is the closest you'll get to uphill on water. While you may not be going any faster it keeps you more planted on your course and you get thrown around a little less in my experience. On flat calm lakes there's not much point lugging a heavier motor around, my 90 is at the far end of the weight perspective at 52+ pounds, so after you've lifted that a few times you are liable to throw a 40+ right over your shoulder when pick it up

I grew up boating in an estuary with strong tides, the Seagull/displacement speed argument was sometimes a little mute when people travelling at displacement speed were often going backwards in real terms, when on a dingy a 4 hp Johnson/Evinrude/Mercury/Archimedes Penta could force it considerably beyond it's displacement speed guaranteeing forward progress. I recall many instances when one had to focus hard on the land to see if you were actually moving, often in some of the fastest running areas this experience could last for quite some time - but heck, we had more time back then and as a kid it seemed fun