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Hello and allow me to thank you before hand for taking the time to read my post.

I just got a 1965 16/17 Currituck with 2000 Nissan 50hp 2 stoke and I think I am over propped.

With my normal load and the bimini top up(two people on board (280lbs) 10 Gallons of Fuel, battery, life jackets, anchor, et) at WOT and fully trimmed I cannot get the RPMS past 4300. I believe this motors top RPM is supposed to be between 5200 and 5800. I am currently running the stock Nissan prop which is 11 X 12.4. I did not have my gps but I am guessing I am traveling around 25-30mph, but with this setup (assuming I had the correct prop) I figure WOT should get me low 30's at 5600 RPM. This was on flat calm water and the boat has no problem popping up on a plane at all, in fact it seems to get up to fast.

The gear ratio is 1.85:1

Do you guys think the prop is wrong?


Thanks,

Matt

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The prop may not be quite right, but I suspect the motor is not running on all three cylinders and that is you main problem. That boat should be able to do 30 MPH and at only 4300 RPM with that prop it is doing less than 25 MPH now.

There is no way a 12.4" pitch prop should be so far off unless the boat is VERY heavy.

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Perhaps that is the case.

The motor has 115 hours on it, but has been sitting for a while....

Starts up perfect and idles fine, but I do notice some power surges while accelerating, so maybe thats the third cylinder kicking in and out? At WOT, there are no surges at all, but like I said I cant get it past 4300 with the prop gripping the water. If I trim the motor out causing the prop to slip, my RPMS Spike up to 5800, but my speed decreases, once I lower the prop and get it to bite again, it levels out at 4300 RPM.

If it is indeed a cylinder not firing, do you have any suggestions on where to start trouble shooting?

Thanks again,

Matt

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Okay I fixed the motor problem (Hi speed jets on carb were clogged) and now would like to fine tune to the correct propeller.

Now with the current prop (mentioned above) with a normal load and fully trimmed my RPMS reach about 5400-5500 and moving around 30-32moh. The recommended WOT RPM for my engine is 5200-5800.

Boating in the keys, I would like a stainless steel prop. Do you guys think given the above data that I should go for a 12" pitch or 13" pitch prop?

Any good recommendations on SS props this size?

Thanks,

Matt

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I would think a 12" pitch stainless prop would get you closer to your 5800 rpm max. By the way I have a 40 tohatsu and was thinking of cleaning my carbs. Were you able to do yours yourself.

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The pitch you need depends to some degree on what propeller you use; there is more to propeller selection than just pitch.

Having said that, there are not a lot of options in this size class. You probably do not want to increase the pitch because that will drop your RPM and they are about as low as you want them now.

For small, class "C" propellers with 3-1/2" hubs, these are your options:

Solas makes the "New Saturn" in the "C" class and they have pitches as low as 8". You would probably want their 11-3/8 x 12, part #5331-114-12

Mercury offers the Vengeance all the way down to 9" pitch. You would probably want their 11 x 12, part #48-855856

I like the Stiletto Triad 3.5 but the lowest pitch they offer is 12" and I know from experience that their 12" pitch will perform like a 13" from everybody else, but if you use them you want their 10-1/2" x 12", part #C 802312 with a C-013 hub kit.

PowerTech and Michigan also offer props in this class.

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Where is this Nissan mounted on the transom? How high is off the top of the transom?

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tom blinstrub,

The carbs were super easy to clean. It was my first time cleaning carbs and I did all 3 in under an hour. Just pay attention to the linkage.

Tom W Clark,

The motor is is mounted so that the bracket that mounts the motor is on top of the transom. I am thinking it might be mounted to low? I could raise the motor but then the bracket would be off of the transom... is that okay?

Also, Thank you for your help and responses.

How do you post pictures here?

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[IMG]http://i1193.photobucket.com/albums/aa341/mskin003/whaler3.jpg[/IMG]

[IMG]http://i1193.photobucket.com/albums/aa341/mskin003/IMAG0162.jpg[/IMG]

http://i1193.photobucket.com/albums/a...AG0152.jpg

EDIT:
Maximum of 2 inline photos allowed in the forum area. Thank You

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Yes, the motor is mounted too low.
It needs to go up one or two bolt holes.

Looks like this is a "Custom" model as the interior is not original.
Here is an original Currituck with original interior.
http://www.whalercentral.com/userphot...lbum_id=32

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Joe Kriz,

I know this is not the original interior. The previous owner custom built that seat and put in a center console, but you can still see the filled in holes from the original currituck interior.

So the consensus is to move the motor up a hole or two? This would have the outboard bracket not resting on the transom....is that okay?

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Absolutely OK....

There is a Standard Mounting hole pattern for all outboards.
The upper holes are generally drilled 1 7/8" to 2" below the top of the transom.
The motor is then mounted up from there if needed.

We are never sure what a member knows about their boat as we have seen just about everything.
If the boat no longer has the original interior, then it has been customized and becomes a "Custom" model. That way we all know what model a member has. Someone new to Boston Whaler boats and looking at your model thinking it was a Currituck would not be accurate. That is the main reason we call the model what it is.
There is absolutely nothing wrong with a Custom model as long as everyone knows that's what it is. Less confusing for all of us.

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Thanks Joe,

It is a custom then, I prefer the center console set up for fishing/diving. Its a great little all around boat.

So when I do indeed raise the motor, what type of improvements should I be looking out for during the test run?

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A few things.
1. Generally better boat performance
2. Improved top end speed
3. Better fuel economy due to less drag
etc.....

One of the main things to look at is the spray coming from the cavitation plate. The cavitation plate should be just above the water when running at cruise speed, trimmed properly, and little to no spray coming from the cavitation plate.

Many boats with the cavitation plate (engine) too low will soak the back seat passengers with water spray...

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I agree with Joe. You should raise the motor 1-1/2" (two bolt holes) and with the new propeller, everything will be better including:

- Easier steering and handling.

- Less bow rise on acceleration.

- Faster acceleration.

- A reduced chance of striking bottom with the motor because the boat will draw less.