Motor configuration questions

[Two Happy]

Hello All, We are considering a 22 cruiser and want to know if a 40 hp and 30 hp configuration will push the boat around. We prefer to travel at under 10 knots so we think we would need a much smaller motor than a 40 horse for 5-10 knot cruising but want to be able to kick it up to 20 knots if need be. Would the weight differences cause the boat to be unstable? Primary waters would be San Juans into Canadian North. Or can one primarily cruise with twin forties at low speed without damaging the motors? We have read a 9.9 kicker is of no use in heavy seas so we don't want to rely on a kicker. Thanks!

[MikeR]

Hmmm, interesting idea, but not sure I follow? Why would cruising around with twin 40s be worse for the engines than cruising around with a 40 + 30? There are many who slow cruise with twin 40s, twin 50s, twin 60s, and singles from 75-115 hp, engines with multiple thousand hours of such cruising. I'm sure those with the twin 40s will chime in! Some downsides that come to mind for the 40 + 30 combo - probably lower alternator amperage on the 30 for charging batteries while cruising, and then of course the resale value - aesthetics is one of the coolest things about "twins" (some will argue otherwise)

-Mike

[thataway]

I don't see the reason--a 40 at low speed will do fine--just alternate engines to get equal number of hours. On the other hand, a 9.9 hp will certainly push the boat at hull speed--and putting a 20 on it will do very little more.

Either way, you are paying for maintenance on two motors. The fuel burned on a 30 and 40 at the same speed will be so close that it probably will not noticed.

If you have 30 and 40, there will be a little difference in throttle to get the boat balanced when going on a plane--may be a bit trickey, where the two 40's will have about the same thrust. Weight should not be an issue--just move a battery if it is.

[hardee]

I don't think there is any advantage to the 30-40 setup vs twin 40's, and as Bob mentioned it would take differential throttle settings to maintain a strait ahead course. I slow cruse with twin 40's quite a bit, usually with both running, but at times on a single also. Either one works, but the throttle speed (RPM's) are lower when running the twins than it takes if running a single to maintain the same speed.

Harvey
SleepyC

[South of Heaven]

Get twin 40s. Many of C Brats have that setup and love it. No need to reinvent the wheel!

[ken35216]

What is this "slow cruise" and " under 10 knots" nonsense? I don't like going too fast but these boats are made to plane and that's the reason I bought mine. They have the perfect cruising speed for me (18-22 mph)

[Two Happy]

However, it appears there is no good reason to change the 40/40, especially when taking in all the well thought out considerations posted here. We are looking at a 22 cruiser that has a 90 hp but then that meant us having to put a kicker on. We have read a 9.9 kicker will not push the boat in a four knot and above current should we have an emergency with the one larger motor. The 40/40 makes a lot of sense since a 40 will push the boat in an emergency. Does anyone have experience with a 9.9 kicker in 4 knot and above current? And with regards to speed- to each their own. As for us, we prefer to cruise at low speeds but have the option to kick it up when needed and so that is why I posted the question about efficiency and possibly damaging the motors if we want to cruise 90 percent of the time at 5-10 knots max.

[BillE]

Your under ten knots will likely be done at about half of that. Above that you will either be on plane in the low teens or plowing a huge wake around 10mph.
The 9.9 will be plenty to push a 22 at slow speeds but I do think that you will prefer cruising with your main engine. I would recommend that anyone wanting to slow cruise on a C-Dory try doing just that on one before purchase. These are not at their best cruising that slow, imo, and I find mine much more enjoyable in the mid-teens.

I used to enjoy poking along in my 22' sailboat with the kicker at around 5mph, but I had a keel that kept me tracking straight and a rudder that gave great control. Both are missing on a C-Dory!

[Hunkydory]

Two Happy, I’ve run many thousands of miles at displacement speed switching back & forth between our twin 40’s as Bob suggested. I now have about 2365 hours on the twin 40’s & they would be over 4000 hours apiece if both had been run all the time instead of switching back & forth between. Most of these slow cruising miles have been done at between 6 & 7mph with both motors down & the non running motor in neutral. The two legs in the water making boat control & ease of steering very good. At between 6 & 7 mph I average about 7 mpg on one motor & 3.5 on plane with both running. I normally cruise with a very heavy boat set up up for long range cruising. There are many good reasons for slow speed cruising in a CD22 with fuel range extension between fueling my number one reason, but for those of us who are into enjoying the cruise not just getting some place it’s an enjoyable alternative. The even better part is if needed or wanted both motors can be turned on, power upped & much higher speeds can be obtained & held. I think you will eventually find you go back & forth between displacement & higher speeds & enjoy the advantages of both. I will be starting another thread on why I’m now replacing my 20 year old Honda 40’s with new Honda 60’s.

Jay

[ken35216]

[hardee]

[Hunkydory]

[quote="hardee"]

[thataway]

Two Happy: