Twin Suzuki 60s on CD22

Running one of the 60's may get the boat on plane, but by definition you would be lugging it. propped for twin application, the motor would not be able to get to the recomended WOT as it will be doing twice the work it normally does.

In an emergency- fine. Normal use, run both engines.
 
Matt Gurnsey":8wtno5di said:
Running one of the 60's may get the boat on plane, but by definition you would be lugging it. propped for twin application, the motor would not be able to get to the recomended WOT as it will be doing twice the work it normally does.

In an emergency- fine. Normal use, run both engines.
Click to expand...


Matt: What be the affects of running one motor at displacement speed?
 
I don't know if you can document that there were major structural changes to the transom to account for a larger engine thru time. Most builders will put in a knee, beef up the splash well, put in a heavier core or even change the hull forum to account for more hp. Unfortunately many small boats are not designed by a NA--not that that is always necessary, but it is certainly desirable to have a NA or yacht designer involved. Often increase in hp is requested by the customer, and the factory says "why not--if we sell more boats OK". It is not just weight, it is also the force put on the transom.

Joe C states that the boat goes into an unsafe zone at 38 mph--from my experience with C Dories (and other similar boats) I would agree that handling and safety would be compromised by going that speed. As I have stated many times, my feeling is that the boat becomes a bit unstable at about 30 knots. Why take a risk that someone will take the boat beyond its safe handling speed.

I can see the argument if you were going to be running the engine at high elevation, and felt that the 100 hp would not be enough to get to a decent cruising speed.

Jingram, I apologize if you took my post to be "too stern or almost a bit indignant". However, I have spent much of my life involved with boating safety, and I see a lot of people who do not have the knowledge of boats who do things which are not wise. I invite you to describe to us your boating experience, and experience in these types of boats.

I also agree on the issue of lugging a 60 trying to plane the boat. (especially with any load). I examined a Pensacola boat for two potential buyers which had a Honda 50 on it, and the owner could not get that boat to regularly exceed 12 to 13 mph, so he ran it at displacement speed. I would never buy a boat just because 10 hp more "might" plane the boat in case of a lost one of two motors. Again, modern outboards are so reliable that it is very rare to have a failure, unless it is contaminated fuel or lack of electrical power.

There are reasons that a new Suzuki may bet better mileage than a carbureted outboard. Part is the injector system and the lean burn system. I am sold on Suzuki outboards.

As I said, it is your money and your boat--do what you want. You have both sides of the argument.
 
Bob again, not sure why I sense so much hostility from you about this. You are right, it is my money and I will do what I want. That being said, just so we are clear, the question originally posted wasn't as to the merits/detriments of dual 60s, it was whether it was even doable from a legal/dealer perspective.

As it is, I appreciate the input and the ensuing discussion the thread started. It was great to hear pros and cons and to understand various people's experiences. That being said, I didn't really sense any hostility except from you. Just because people are debating the merits of something on this forum and "questioning" what may be the status quo, doesn't make it a bad thing. After all, if that was the case, you would all be running 70hp singles on the 22 eh.

I never once said I was looking to go "fast" or that I was "bent" on 60s. If anything my thinking was that I might be able to run at slightly lower RPMs and increase fuel economy as a result AND that I might be able to get on plane a bit easier on a single 60 than a single 40. Clearly I will be lugging the motor if I do this, but this is a function of prop more than anything else. Correct?

As for the force on the transom... I would argue that would be torque dependent more than anything else regardless of how much horsepower you are running. In fact, a big torquey 115 two stroke could put far more stress on the transom I would think than twin 60 4 strokes with lower overall torque numbers. Am I crazy for thinking that?

The wonderful thing about this thread is that we were able to discuss this and talk about both sides instead of it just being a "go with twin 40s and be done with it" thread because that is what WE have and we said so. I don't find those threads very constructive. Maybe I'm in the minority though.

The input provided from EVERYBODY, including you, has been very much appreciated. Thanks for sort of bench racing with me and debating the pros and cons. It was really helpful and hopefully if/when this comes up again in the future, it will be equally helpful then.

Cheers! :beer :cigar
 
Jingram, many thanks indeed for a very thought provoking topic. Translate torque into thrust and you paint a good picture.

If you have more torque available then you have more thrust and more strain. Indeed, one could make an argument that distributing the thrust between two mounting locations, neither of which is at the boat centreline may actually reduce localised strain. I've seen that result where twin 1200hp gas turbines produced less strain than a single 2300. We will probably never know in this case because I doubt that anyone will ever do an FEA or strain gauge a CD22 transom and so do controlled testing.

Hammering the throttle(s) will obviously put much more strain on a transom, regardless of the type of propulsion. Operator input will be a big factor in assessing transom integrity over time.

Matt's rule of thumb is probably a good one and his other comments make a lot of sense. Once again, thanks for stirring the gray matter. After 40 years + working with propulsion systems I still love to discuss these things.

:beer :beer
 
Guys
My boat is an 06 model and with the twins will run a hundred miles on each tank. Know this because the boat goes in the gulf anytime it is calm
and my trip speedo. In rough water on the river that I live on the twins deal with crossing ski boat wakes much better also maneuvering around the dock much better. Offshore we troll on 1 much better fuel burn. My last statement I think the boat is dangerous at 24 25 mph 38 mph is
crazy but it will do it maybe more. Honda quit 1 time hade to run back 30 miles on the Tohatsu 6hp kicker never again
Joe
 
If more is better how about a pair of Yamaha 70's they only add another 28 pounds each? I'd be careful with Bob as he is a valuable resource. I reread his replies I did not see any hostility but that's just JMHO. Certain things are probably better left unsaid if you want the best out of this forum. Good Luck with your choices.
D.D.
 
Hi jingram, i'm not seeing Bob as hostile on this one, he has a lot , I mean a lot of time on the water and been there done that. He just wants us all to be safe and not get into a corner where we can't get out of. It used to be 70 hp was all folks fitted on the cd22 as we go along, we get more stuff and more neccesaties and hence need more power. I just looked at QT in the Harbour here yesterday, visitors from Florida. They are cruising thru and his waterline forward is a good 4 inches visible. How the heck do they do that? That is the factory waterline which hasn't been changed in the mold for years I bet. I have been full time aboard my boat a lot and I had to raise my waterline 3 inches from factory and change my prop. I have full time liveaboard stuff for 2 aboard. My 90 still pushes all that at 25 knots in flat conditions. Halcyon has some 24000 cruising miles on twin 40's and is still cruising. Twin 60's I am sure as kitsap marine said are do able and you will probably never go wot. I lean toward it being a bit experimental and may be a challenge come resale time. Best of luck on your new boat. George :thup
 
Hello jingram, did you know a chevy 350 will fit in a cavalier if you use a shoe horn? With the right gearing it may even get good fuel economy. Could you do it yes, should you no! Thataways advice and comments are said for good reason because he knows better than most. You asked the question, be prepared for the answer. Redfox has been using the new Yamaha 70 with great success for quite some time and others with 80 hp including myself have more than enough power. Remember that the 22 was designed for 75 hp. :thup
 
Well clearly, I totally blew things out of proportion or misinterpreted tone and for that I apologize.

Bob, once again, just so we are clear, my apologies to you.

Chimoii... so help me out here. I've read that prop diameter has little to do with thrust or torque. Pitch does. According to what I have read, the prop doesn't deliver torque. It provides thrust based on torque applied to it by the engine. Is that the case or am I missing something?

You are absolutely right, I was using torque incorrectly since ultimately it is the thrust being provided by the props that are spinning up hard do to a torque dump by the motor that would ultimately put the most strain on the transom. I definitely think it could be harder on the transom with one bigger block motor than two smaller twins. The load, as you indicated would be slightly more spread out on with the twins instead of localized to one spot in the center of the transom which is the weakest point in the span.

This stuff really is interesting!

Will C -
If more is better how about a pair of Yamaha 70's they only add another 28 pounds each?
Click to expand...

Again, the original intent of the thread wasn't about maximum power or going fast or the merits and demerits of how much power is too much or too little. It was purely about whether or not it was even doable from a dealer/legal perspective. I've reiterated that several times.

I'd be careful with Bob as he is a valuable resource. I reread his replies I did not see any hostility but that's just JMHO. Certain things are probably better left unsaid if you want the best out of this forum.
Click to expand...

As for being careful with Bob. What is that all about? I understand and appreciate everbodies perspective and I was nothing but polite in the thread. That being said, what is there to be careful about? This is an internet forum where dialogue should be encouraged, not discouraged.

Bob and I are big boys. That being said, Bob did PM me last night. Clearly I must have rattled the hornet's nest a bit. An interesting experience to say the least. He reiterated that he is just looking out for folks's safety, which I can appreciate. Hopefully it ended on a good note.

Again, thank you all for input. It has been helpful and enlightening.
 
Since we're just spit balling ideas here-

Has anybody got twin Yamaha High Thrust 50's for power? I'm wondering what the larger diameter props would do for performance? Or would any benefits be negated by the increased drag of larger lower units?

The Evinude has the larger gearcase standard and the twin 50 and 60 E-Tec powered boats seem to be good performers.

Just thinking out loud....
 
Jingram - I have been running the CD 22 for about sixteen years. The first had a 90 Honda and the second a 115 Merc. Thataway's comments are sound. The only reason I went to the 115 was because I now boat at altitude, near 8,000 feet which translates into a 24% drop in power compared to boating at sea level. On Yellowstone Lake at WOT with several passengers and gear, the top speed is 27 mph with the 115, but in the mid 30s mph at 3,000 feet, much too fast IMO for secure handling even with tabs. I use a 13" wheel. If I were boating at sea level, a 90 hp of any make would be just fine. Plenty of power. I find the tab setting at 60% and 4,000 to 4,200 rpm to give a firm, yet reasonably efficient way to go at speed. When time is of no concern, I cruise flat at 1,000 rpm and get close to 10 miles per gallon of fuel. Of course all of these figures have to be adjusted for weight aboard, wind, current, etc.

Have some info from a mechanic up here in Yellowstone about the Honda 40 with carbs. The outfit which rents boats at the marina has equipped a fleet of 16' Gregors (w/ swept up bow) for tourist use - 16 skiffs. These are used hard for 3 mos of the year, and usually run wide open in very cold water by people who know little about marine motors. Each motor is run for about 5 minutes before the tourists start using them. With routine maintenance, these motors are almost without exception trouble free. bullet proof in the words of the mechanic who is very experienced with marine motors of many makes. When the tourists runs into the bottom along the shore which has fine granite gravel and specs of obsidian which gets sucked up into the water pump and cut up the impeller, nothing else seems to go wrong according to him. He feels all outboards while in service should be started up daily and run for a few minutes even if not used for propulsion. Food for thought.

Yellowstone John
 
I'm with Thataway. Even if you over power just a bit, you are opening up yourself to problems if there is ever a cause to be looked at closely by law enforcement. Its an unnecessary liability risk.
 
A lot of you mention top speed and I don't think anybody here disagrees about there been a very finite limit to the safe handling capabilities of the C-dory hull. Everybody pretty much agrees that above 28-30 and things get squirrelly in a hurry.

Out of curiosity, are you all happy with the overall "pep" of your setups loaded for cruising? I'm not talking about neck jerking speed out of the hole shot, but rather, ability to quickly get up to speed as you ramp up throttle when you are running a typical cruising load... full fuel, water, and at least two people, plus whatever you are packing for food, beverages, etc.

Are most of you happy with throttle response and ability of the motors and the boat to respond to throttle commands quickly in these situations or those of you running say twin 40s or a single 90, does the speed come on more gradually and throttle response is more sluggish?
 
jingram":1gvw7o68 said:
A lot of you mention top speed and I don't think anybody here disagrees about there been a very finite limit to the safe handling capabilities of the C-dory hull. Everybody pretty much agrees that above 28-30 and things get squirrelly in a hurry.

Out of curiosity, are you all happy with the overall "pep" of your setups loaded for cruising? I'm not talking about neck jerking speed out of the hole shot, but rather, ability to quickly get up to speed as you ramp up throttle when you are running a typical cruising load... full fuel, water, and at least two people, plus whatever you are packing for food, beverages, etc.

Are most of you happy with throttle response and ability of the motors and the boat to respond to throttle commands quickly in these situations or those of you running say twin 40s or a single 90, does the speed come on more gradually and throttle response is more sluggish?
Click to expand...

I had a 22 with twin Honda 40's. Lightly loaded that was enough to get just up to where the handling would get squirrely at wide open throttle. The hole shot was fine and I'm sure I could have water skied behind it if I wanted to. Once I had permatrims installed it got on plan a bit quicker. Without the permatrims, the bow would rise up a bit for 2-3 seconds before rolling back down once we got on plane. With the permatrims, this happened a lot faster and the bow never rose 1/2 as high.
 
I run the twin Honda 40's & don't want or need to run anywhere near a top speed of 30 mph.   We run either very heavy on our Southeast Alaska cruises or medium at Yellowstone's high altitude, so are now propped for either with a 10x12 stainless prop  that from memory gives a max speed of 21 mph at 5800 rpm.   The hole shot is satisfactory with a ease of reaching planing speed.  I have yet to find a bad water situation where more power would have been useful, but have no doubt that it could happen.  In my situation having both Permatrims & trim tabs is a necessity for the way the extra fuel & other stuff for long range cruising is distributed.  On our resent three month Alaska cruise of 2100 miles approximately 86% was done at displacement speed & only 14% at roughly 4500 rpm & 14 mph.  14 mph is my preferred cruise speed when on plane, so this worked well for us,  but there is another situation where I believe more torque & perhaps hp would be very  beneficial & that's when running on one motor at displacement speed.  There it takes almost 3000 rpm to do 6 mph & 3500 to do just over 7 mph, so can not come close to Yellowstone John's 10 mpg & at 3500 rpm am concerned about possibly lugging the one motor, so only rarely do so.

Jay
 
I think the main reason the factory upped the horsepower rating from 100 to 115 was that almost no one had 100hp motors for sale anymore and for whatever reason 115hp became the new spec. There was a case with a Tomcat where a dealer put on two 175 hp Suzuki's on the boat that was rated for two 150's. They called the factory and the weight was the same so the factory gave their approval for the higher horsepower. Rigging a boat so it's easier to get into the squirrelly zone of beyond thirty mph in the case of a 22' cruiser and spending extra 1000 dollars money to do it seems like something only a government agency would do. I would be happy with twin forties or twin 50's. If I had it to do over I would have rigged our boat with twin 70's if the new Yamaha 70's would have been available at the time.
D.D.
 
Back
Top