Prop Exchange?

[cpostis]

Brilliant, thanks!

SS, 17" pitch. Depending on the prop manufacturer, the prop diameter for this pitch will be 13", 13.25", or 13.5". Right hand rotation. 15 spline.

I plugged in your boat/motor specs.
This is what their recommendations are:


Are you sure you are getting max performance from your S115?

[99yam40]

Brilliant, thanks!

SS, 17" pitch. Depending on the prop manufacturer, the prop diameter for this pitch will be 13", 13.25", or 13.5". Right hand rotation. 15 spline.

edit
after seeing the above post you need to remove you prop from the adds you posted and find out what is wrong with your rig.

Need to find that test wheel

here is another web site to look up performance of a rig close to yours.
make sure to click on the show archive
http://yamahaoutboards.com/owner-res...ance-bulletins


Did not see a 17 ft boat listed, but did see a 16.9 one with a 23" pitch,
but it is a lighter rig

[pstephens46]

I assume there are different types/sizes of test wheels? Wonder which one he would need? If he could find one to borrow etc....

[99yam40]

he said he looked for the correct one Rod told him about I believe

Here is a 17.5 rig bulletin from that web site I posted http://yamahaoutboards.com/sites/def...5xl-115tlr.pdf

[pstephens46]

Didn't recall if Rod specified a test wheel for OP. He has on other threads from time to time. Wonder if Boscoe has a list? Might be interesting to see the full list of what is available.

Not sure what type of boat an 170 Aquasport happens to be. DC,CC or Bass Boat?

[TownsendsFJR1300]

When I was on the Marine Unit (police Department), our first boat was a 17' Aqua sport which was a center console.

It was not a deep vee at all and a pretty low transom. Certainly not a flats boat but not a rough water boat.

One of the guys on the unit left it tied up to the dock when a strong front came thru kicking up the water. Sunk the frigging boat... At least it had a Mercury on it..

[rodbolt17]

find test wheel YB1624.
it should spin it at 4900-5100.
if it can prop it correctly.
if it cannot fix the engine.

[Jason2tpa]

Appreciate all the input guys. Many of you replied, I'll address all here:

99yam

here is another web site to look up performance of a rig close to yours.
make sure to click on the show archive
http://yamahaoutboards.com/owner-res...ance-bulletins

Here is a 17.5 rig bulletin from that web site I posted http://yamahaoutboards.com/sites/def...5xl-115tlr.pdf

The boat in this bulletin is a bass boat, no where near a similar hull design as AS.


The boats used for these bulletins do not relate to the specs of my hull, even those whose length are 1-2ft longer. A '76 Aquasport is a unique hull design, those who are experienced saltwater boatsman know it when they see it. These days, 40 years after the hull production, you'd label it a "bay boat". But it's not built like the bay boats of these days. Low deck, high gunnels, 20" transom height yet a deep modified vee. The majority of the 1100lb dry weight is rear. Add the weight of engine, fuel, console, etc, to the rear and you've got a boat sitting low at the transom, high at the bow.

cpostis

I plugged in your boat/motor specs.
This is what their recommendations are:


Are you sure you are getting max performance from your S115?

Who is "their"? I'm not sure what specs you plugged into their webpage but the results greatly differ from when I do it. See the pics below for just 2 examples of online prop selector guides, using the specs of my boat/motor. The first is Yamaha's prop selector, the second is Michigan Wheel. As you'll see, neither suggest a pitch as high as 21", which ironically is the pitch of my propeller. Now, it's possible whichever prop selector you used is giving results for props that only THEY carry–they being the webstore or business you're using to select prop. The brand names of those props listed are all OEM Mercury.

pstephens46, townsend: See above description of the classic aquasport hull. There are no modern hull designs similar to the late 60's to mid '70s Aquasport, Mako, or Proline–which is probably why you know one when you see it, and why these hulls are so often restored from the shell up. That and they have a stellar reputation for being built incredibly good, durable, and performance.

As far as the test wheel, I mentioned in my first post they are very difficult to come by. I have contacted every local yam dealer, private yam mechanics, and propeller shops. No one has a test wheel.

[Jason2tpa]

A few pics of what a '76 AS 170 looks like

[TownsendsFJR1300]

That is about the same as we had. But we had a hard top (for lights, cop radio, VHF etc, on it)

Ours was in the mid 1980's, worn out by the Sheriffs Department and given to the city PD which we used for sometime.

And the engine was too large for the hull so it sat even lower in the rear...

I'm very familiar with that hull....

[Jason2tpa]

One last important note that needs to be clarified again. The motor IS performing within spec rpm range, albeit the bottom. Dropping prop pitch by 4" gets motor to top rpm spec = top hp.

[pstephens46]

Not bad to be 40 years old. Sorta looks like some of the Parker's.....

Go look at the Parker 1801 on the performance bulletins....Still a weight difference...

Or this:

http://yamahaoutboards.com/sites/def...bay-f90tlr.pdf

[Jason2tpa]

That is about the same as we had. But we had a hard top (for lights, cop radio, VHF etc, on it)

Ours was in the mid 1980's, worn out by the Sheriffs Department and given to the city PD which we used for sometime.

And the engine was too large for the hull so it sat even lower in the rear...

I'm very familiar with that hull....

Mid 80's AS 17 is the Osprey model. Completely different hull design than the original Walt Walters designs of the mid 60's to late 70's 22-2, 19-6, and 17-0 models.

On the same property as my local boat ramp is also a USCG office and FWC office. The FWC boat lot has so many different boats it's ridiculous. Speaking with an FWC officer I've become friendly with, I told him it must be so much fun going out on the water on a different boat everyday. He smiled.

[pstephens46]

Mid 80's AS 17 is the Osprey model. Completely different hull design than the original Walt Walters designs of the mid 60's to late 70's 22-2, 19-6, and 17-0 models.

On the same property as my local boat ramp is also a USCG office and FWC office. The FWC boat lot has so many different boats it's ridiculous. Speaking with an FWC officer I've become friendly with, I told him it must be so much fun going out on the water on a different boat everyday. He smiled.

Maybe this guy will let you borrow a few props?

[Jason2tpa]

Maybe this guy will let you borrow a few props?

Haha. Or better yet, the 37 contender with trip 300's. Id borrow that!