Prop Exchange?

[pstephens46]

I don't know if you you need a 13, 15 or 17 pitch. But my gut feeling is 21 is too much for your boat......based on what I saw today.

[Jason2tpa]

I don't know if you you need a 13, 15 or 17 pitch. But my gut feeling is 21 is too much for your boat......based on what I saw today.

A reputable prop shop nearby me, Admiral, who has been in business 50 years, stated the same. What was a little surprising to learn is what their theoretical belief was concerning rpms when changing pitch. I've scoured the web, looked at numerous websites containing propeller information. All gave the rpm change of 100-200 rpms per inch of pitch. However, Admiral believes this change in pitch per inch translates to 250-300 rpms. Of course, he also noted many other propeller factors are involved with the max rpm. Note to mention engine and hull factors.

The guy I was speaking with at Admiral's did believe the 21" was too much pitch, suggested I drop to a 19" or the lowest of 17".

[TownsendsFJR1300]

Well, (besides the info here), you have a prop you KNOW how it performs and your current WOT RPMs.

I would go down to a knowledgeable prop shop, bring your prop and tell them what RPM's you need (what you have now) etc, ie and then what prop he recommends... These guys deal with this on a daily basis...

That's what I did, and he nailed it the first time...

[Jason2tpa]

Well, (besides the info here), you have a prop you KNOW how it performs and your current WOT RPMs.

I would go down to a knowledgeable prop shop, bring your prop and tell them what RPM's you need (what you have now) etc, ie and then what prop he recommends... These guys deal with this on a daily basis...

That's what I did, and he nailed it the first time...

That's exactly what i did while at Admirals. They recommended the 17" or 19", and I could return say the 19" for the 17" if it didn't perform as expected. However, the props they quoted me are $100 more than what I can pay elsewhere for same prop.

[TownsendsFJR1300]

Well you may save $100 BUT if you can't return it, your screwed..

It's nice to support your local folks too.. And there's no shipping, return
shipping costs, and you can do it all in a day or two... But that's your call.

For the lack of headaches/frustration going locally it'd save you, may be worth it...

[cpostis]

That's exactly what i did while at Admirals. They recommended the 17" or 19", and I could return say the 19" for the 17" if it didn't perform as expected. However, the props they quoted me are $100 more than what I can pay elsewhere for same prop.

So confusing to the consumer! But that $100 may well be worth it in the end. I'm going to the marine liquidator I spoke of tomorrow to see if they have any/all of the pitch props we have all discussed. I'll inquire if exchange can be made until satisfactory results are obtained.

I do have another question, your 1976 Aquasport 170 is foam filled, is there a chance the foam is water logged?

Anyone, have you been able to access test props or service dealers that will test for you at minimal charge? Not me!

[cpostis]

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

99yam
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

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.

Jason, I used https://www.mercurymarine.com/en/us/...tor/#/step-one

Just now I used Yamaha's prop selector Yamaha.net and got near the results you posted. However I estimated your top speed as you did not post. What is your top speed with the 21" pitch prop?

[Jason2tpa]

Just now I used Yamaha's prop selector Yamaha.net and got near the results you posted. However I estimated your top speed as you did not post. What is your top speed with the 21" pitch prop?

The yamaha prop selector does not ask for top speed. It asks for top rpm at WOT (4500).

[cpostis]

The yamaha prop selector does not ask for top speed. It asks for top rpm at WOT (4500).

I'm sorry, you are right. Mercury, not Yamaha, does ask for top speed for the best propeller selection method.

[Jason2tpa]

So confusing to the consumer! But that $100 may well be worth it in the end. I'm going to the marine liquidator I spoke of tomorrow to see if they have any/all of the pitch props we have all discussed. I'll inquire if exchange can be made until satisfactory results are obtained.

I do have another question, your 1976 Aquasport 170 is foam filled, is there a chance the foam is water logged?

Anyone, have you been able to access test props or service dealers that will test for you at minimal charge? Not me!

Foam stringers. Is there a chance stringers 40 yrs old have been water penetrated? There is no evidence of such, though i wont say for certain due to age.

Thks for checking for me. I have not came across exchange prop service. I likely have to sell it privately.

[pstephens46]

Can someone tell me what the hell is the reason for all that foam sprayed into hull interiors? Nothing but trouble. Sorry to interject....

[TownsendsFJR1300]

Can someone tell me what the hell is the reason for all that foam sprayed into hull interiors? Nothing but trouble. Sorry to interject....

Supposed to be for flotation but my neighbors Mako, the foam held water and rotted the top of his aluminum fuel tank...

[rodbolt17]

we actually have 2 1624 test wheels at Joe's marine.
you may be able to use one if you pay shipping both ways.

[Jason2tpa]

we actually have 2 1624 test wheels at Joe's marine.
you may be able to use one if you pay shipping both ways.

Kidding me?!? I'd totally take that offer. I just tried to PM you with my contact info. Says your inbox is too full to accept. You must be a popular guy.

[pstephens46]

Now we talking! How bout that!

Please video this test if you decide to accept his offer! Inquiring minds would like to wish they were there!