Why is my 16 with a Honda 40 so slow?

S

Stan Major

New member
Just got back from St. Augustine where my return trip speed topped out at about 12 to 13 MPH at 4400 RPMs. I know weight can be a problem (packed a lot of stuff for the trip). What else could be slowing me down? Marc, if you are seeing this, I met Frank with his 2008 Ranger Tug he purchased from you. He was parked 3 slips away from me at the Conch House Marina. Frank lives in my town and says to say hello.
 
Hey Stan:

I have a 16 Cruiser with a Suzuki 50. When we're (2 adults) loaded out for an overnighter I've found my 16 to be slow, too. It struggles to get up on a plane and unless I have a long run it won't come up to full throttle rpms.

If you look at the USCG Max, Capacity plate it'll give you a clue. "4 Persons or 700lbs. or 1150 lbs with persons, motor and gear". With two adults, 12 gallons of gas, two batteries, water, food, etc. it doesn't take much to overload. The boat will safely handle the extra weight, but you'll sacrifice speed.

Hope this helps, be safe out there. :)
 
We had a 1993 16 with a 40HP and could run 16 to 18 MPH at 7700 feet on Yellowstone Lake, with 2 people and no gear, in smooth conditions. Add 2 more people and we were at 12mph or slower. They are very weight sensitive. I suggest going out for a run with no gear and one person, then start adding people/weight to see how weight affects your speed. We used to place lots of gear in the birth to balance out the boat. My experience is tht 16's tend to be stern heavy with batteries and full tanks. I ran with only one battery.

Kevin
 
Is the 4400 RPM at wide open throttle? If so, you need to get another prop, with considerably lower pitch for times that you run loaded. The aluminum props are not expensive--and you should at least get 5500 RPM at WOT. I suspect dropping the pitch by 2" you will see significant improvement.

Of course the other question is what prop is on the boat now--and compare to what others get. The 4400 is a decent cruising RPM--but some folks will run the motors faster, with no harm.

The other question is do you have a Permatrim or trim tabs. With weight, this can help trim the boat for a better speed.

Give Marc a call, PM, or E-mail--he is always very responsive. However I believe he had a boat show this weekend.
 
With Patty and me on board, crab pots, pot puller, and maybe lunch and water, our 1991 CD16 Angler with the 1991 Johnson 2 cycle 40 goes faster than feels comfortable. Even when we had it loaded down for the couple of times we took it for overnighters (not Patty's cup of tea), it still had plenty of speed. I think the issue here, once again, is the inherent stern-heavy design of the Cruiser as compared to the Angler. The Angler literally pops up on plane effortlessly, no tabs or Permatrims required.
 
Stan, I have my 16 Cruiser set up much like yours. 40 hp Honda with a Permatrim, two batteries and two 6 gal fuel tanks in the stern. It is loaded forward with about 150 to 200 pounds of gear.
The Honda hits about 5200 at WOT, with a top speed of about 20 to 21 knots. I cruise at 14 to 15 at about 4500.
If your engine is running 100%, then the variables here, I would think, would be total weight carried (and weight distribution fore to aft) the prop size and possibly bottom growth.

Robbi
 
As I read your first post, I was thinking along the same lines as a couple of other responses:

1) Do you have growth on the bottom or prop? Especially if it is barnacles. First step would be to clean it off, if so.

2) 4,400 RPM at WOT sounds quite low. Your manual will give a range of recommended RPM at WOT, and you should generally be in the upper half of that range (it's typically somewhere between 5,000 and 6,500, but check for your specific engine). Change the prop to achieve this. Test in an "out and back" pattern to eliminate any effect of current, etc.
 
I'm not sure this adds any thing to the discussion but, while performing other work a mechanic suggested that that our prop should be changed from 11 to 14 pitch. I did it and now we attain our comfortable cruising speed of about 12 or 13 mph at 3400 rpm. Lots of room left on the throttle but we don't want to go any faster.
 
I believe this is a "cruiser thing". With my 200lb self and my larger fishing buddy, a kicker, crab pots and fishing gear my angler with yamaha f50 cruises comfortably at 13 mph and wot at 21mph. I think the cabin forward makes the sifference.
 
Thank you all for the input. I would be happy cruising at 12 and all out at 21. I don't particular like to go that fast myself. Here is where I am at in my research and I still have questions. My current propeller is a Power Tech Stainless SRD 3 11P-YS50 which is an 11.25 diameter X 11 pitch. Everything I read says higher pitch equals higher speed. The reply from Power Tech is in order to increase RPMs I need to lower the diameter and the pitch. Suggested propeller is the Power Tech REB 3 which is 10.25 diameter and 10 pitch. Question is even though this prop increases the RPMs doesn't the lower pitch make the boat slower? What would happen if I went to a 10.25 diameter and a 17 pitch? Again going with the Higher pitch equals higher speed statement. Someday I will actually understand this stuff. Thanks again for the help.
 
Stan we had a 16 cruiser with 40 Honda .It would cruise easy 13-15 mph and WOT about 20-22 mph but it seemed much faster what i did to compensate the heavy rear end was put a large doel fin on the engine what a difference jumped up on plane with 2 220lb. men in boat We would hit 5200-5300rpm at WOT.
Your problem could be a fuel problem spin off your water seperater filter (you have one ) and empty into glass cup and see if you have water in fuel then replace filter and add non ethanol fuel . Make sure prop is not nicked also loose some of the stuff on the boat. and off course make sure eng. is firing on all cylinders If that cures it no problems if not then look at buying a LOWER pitch prop. Hope that works let us know
 
I had a nice chat with Stan a few minutes ago . There is some growth and my opinion is to go to an aluminum 9px12dx3b and see what that does after cleaning the hard growth for the bottom . he is . That should gain at least 5 or 600 or more RPMs on his EFI Honda 40with a clean bottom, and the slightly larger diameter will help with low speed handling .
Marc
 
I was thinking Solas Aluminum RH AMITA 3 which has a 12.2 Diameter and a 7 pitch. Is the 7 pitch too much of a drop from the 11 pitch on there now?
 
That will likely be too low of a pitch with a clean bottom .I wouldnt think you would neet to go below 8 and I would start with no growth on bottom and 12.2 X 9 p.
Marc
 
The reason that a 17" pitch prop will not work in your case, is that the engine is not turning enough RPM to start with. The prop sort of like screw in the water--and for each revolution theoretically should go 17" forward. (There are also hydrodynamics, involving foil shapes, and higher pressure on the back side of the blade, and lower pressure on the front. An engine has to have enough RPM to spin the prop and achieve its rated RPM at wide open throttle-and when you have too much pitch, you will lug the motor (as you are doing now--with WOT of 4400 RPM--.

Could you put a 6" diameter and 17" pitch, well yes, and you probably could turn up full RPM, but the "slip" of the prop would be huge. A good prop will give you 10 to 20 % slip. You want a happy medium, where you have less slip and most speed at the specified WOT of 5500 to 6000 RPM. Some people "over prop" displacement boats, to get a little better fuel economy--unfortunately this does not work well in planing speed boats.

Here is the link for propeller slip. You do have to know the gear ratio of your lower unit.

http://www.mercuryracing.com/propellers ... ulator.php

If you have bottom growth, you are a candidate for bottom paint--and if you still get marine growth--then either you, or a hired diver should be cleaning the bottom of the boat. When we raced sail boats we cleaned the bottom every week--even with a good bottom paint. We used scotch green scouring pads, or a towel cloth if there was only slime.

There are two excellent books by David Gerr N.A.--The Nature of Boats--has a little on props, as well as a lot on hull design. The other is Gerr's Propeller handbook, which is excellent.

If you don't have the time to read Gerr's book then there are good explanations at:

http://www.boattest.com/resources/view_ ... ewsid=4226
 
Thanks Bob
I am always amazed at your vast wealth of boating knowledge. I spoke to Marc yesterday and I think we figured to try a Solas 3 X 12.2 x 9 Aluminum Propeller RH AMITA 3. The bottom scrapping continues.
 
Satn,

I think that the problem with the CD 16 Cruiser going too slowly is weight distribution. Simply stated: too much weight is at the stern. While there could be other factors involved, this is the most likely culprit. The solution is to move as much weight as you can forward, or if you are overloaded, remove the excess weight.

I had a CD 16 Cruiser for 4 years. When the trim of my boat was balanced evenly, we could reach 25 MPH at around 5400 rpm. We normally cruised in smooth water at around 21 MPH. The other thing that I would be concerned about is that although you may not exceed the weight capacity of the boat, having too much weight at the stern makes the boat dangerously unstable -- at least that is my opinion. I acknowledge that others may not agree with me, but when I had too much weight in the stern, I no longer felt safe in the boat.

Rich
 
Pat Anderson":xedyryrj said:
With Patty and me on board, crab pots, pot puller, and maybe lunch and water, our 1991 CD16 Angler with the 1991 Johnson 2 cycle 40 goes faster than feels comfortable. Even when we had it loaded down for the couple of times we took it for overnighters (not Patty's cup of tea), it still had plenty of speed. I think the issue here, once again, is the inherent stern-heavy design of the Cruiser as compared to the Angler. The Angler literally pops up on plane effortlessly, no tabs or Permatrims required.
Click to expand...

I have a 1990 16 foot Angler which I bought new and powered it with a great little 3 cylinder 30hp Yamaha. I GPS-t the speed with 2 people and 12 gals of fuel with some gear at 21.5 mph (flat calm) no current. Not too shabby--eh. Then on one outing at the mouth of the Fraser River returning against a strong ebb with an apposing NW wind, the waves were stacking up and I clearly knew I was dangerously under powered--end of that motor for me.
I bought a used 2003 50 HP Honda for $3500 and sold the Yamaha for $1000 and repowered Blueback. She now easily run up to 30mph at 6000rpms with a 11.1 X 13 DP prop. I do all my own work as being retired on a fixed income we watch our boat budget carefully.
An interesting side note too. I can troll down to 1.5mph now if need be which is slower than the 30 Yammie and no stink of course from the curse of a 2-stroke wafting into the cockpit.
 
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