Just looking, thanks!

[Boomyal]

The boat is a little 18 footer with a 'knock off' SeaRay hull. It has the 302 with the Merc 1 outdrive (1.5:1). The book calls for a 15 1/4" x 21" prop. This should be a quick little boat. Lightweight, fast hull and sizable motor.

Just checking to see any opinions or experiences for this prop on this size boat.

Also would like to know any bennies of going to a 4 blade and what size that should be.

 

[steelespike]

Re: Just looking, thanks!

What year is the boat?what brand/model? What is the rated wot rpm?
As far as a 4 blade goes generally it is suggesated to drop one inch in pitch going to the 4 blade.
This would depend on the wot rpm and speed and size of the present prop.
A 4 blade will improve low to mid range performance.Better hole shot smoother operation,Stay on plane easier at reduced throttle,
Better handling at speed and around the dock.You would normally lose a little top end but that would depend on the present performance and prop size.
In a very brief search I didn't find any 302s with a 1.5 ratio but if it can twist the 21" up to 4600 with about 10% slip, speed would be about 54.Results would depend heavily on the condition of the hull and the drive train.

 

[Boomyal]

Re: Just looking, thanks!

The boat is a 1976 BeachCraft, made in Salem Oregon. It is 18 ft long with a Merc 888 drive setup. That is a 188 hp Ford 302 and a 1.5:1 Merc One outdrive. The current prop has a tip of a blade torn off and it is (I believe, a 14 x 19)

 

[Tail_Gunner]

Re: Just looking, thanks!

If your go to ss and the motor is healthy a baypro 2 is a kick in the pants....That's a 20 degree hull if i rember right...and if it is the BP provide's lots of lift and midrange punch. Example doing 30 mph and some aproachig wake is coming..2' i can punch my tub and climb right on top of the wake..no bump bump bump..pretty interesting. Yes as spike says they are smoother also a bit like two cylinder bike compared to to a 4cyl.

You will lose maybe 1-2 top end but its nothing compared to what you gain from 0-40..Dont know where you want to run that 302 at as far as wot but here's some info...

4.3 205hp... 2850lbs....18.6"..1.66...19p alum would pop the rev limitier...and do 50
4.3 205hp... 2850lbs....18.6"..1.66...20p 4bl SS BP 2 4900 @ 54

It would appear on the surface that the 302 should push a 18 4 blade ss would be in order the 302 does have more tourqe than the 4.3 does it not....the 1.5 gearing takes you down some in pitch..LIfe would be eaiser if you knew the rpm @ wot was..Hmm i have a 20 you could use but its for a Volvo drive

What speed does that old barge do now 48...51?

 

[Boomyal]

Re: Just looking, thanks!

Do not know the answer to that TG. It currently has about a 14 1/4 x 19 prop on it with one tip mysteriously flapping in the wind, I have not had it out for a test drive. Considering the shape of the current prop (happened while in storage?) I need to get a new one. I do not want to fix that one because it is not near the size indicated in the manual.

As I mentioned, the motor and outdrive look like they have few hours on them so I am sure the motor is top notch. It runs that way in the drive. Maybe I should stick my spare 4 bbl iron mani on it along with my spare Holley refurbed 500 cfm marine carb?

 

[Don S]

Re: Just looking, thanks!

The first thing you need to do is get the engine running, then find out what your WOT rpm's are for the size prop you have on it now. Then you can go looking for a different prop.
You have to get a baseline for your boat by running it to even know what to change to later. Any chart anywhere is just a close guess as to a starting point for a prop, then actual testing on the water is done to find WOT rpm and speed.

 

[Tail_Gunner]

Re: Just looking, thanks!

As you can see the Oracle has spoken..get it done . By the way its not a 23...that would be 23p@4600..1.50 nets 60mph @10% slip.... That's not a power stroke 302 is it...

Better make sure of the gearing Boom if its is 1.50 not a 23 pitched prop...That would take a 300 hp plus engine . Is this not the boat you posted a few yrs ago with the huge bow rail's?

 

[Don S]

Re: Just looking, thanks!

That's not a power stroke 302 is it...

Better make sure of the gearing Boom if its is 1.50 not a 23 pitched prop...That would take a 300 hp plus engine . Is this not the boat you posted a few yrs ago with the huge bow rail's?

LOL, Not a power stroke if OEM, the 888 is 188 HP Ford 302 V8. Nothing special about it. WOT range is 3800 - 4200 rpm.
Came from the factory with 1.50:1 gear ratio as standard equipment from Mercruiser.
The 1.50 gear ratio is about as common as you can get for 5.0L and 5.7L Chevy engines all under 300 hp.

 

[Tail_Gunner]

Re: Just looking, thanks!

Geezz 3800 to 4200.... Well i know that 302 mustand engine..strong in 1st gear but a bit weak on the top end...I thought that engine was a roller 302 HO....age cometh to me. So find a donor 16 maybe 17..(19p nope)..Sorry bro umm yes install the 4 barrel it will keep you nose back in boat's and out of computer networking..:facepalm:

 

[Boomyal]

Re: Just looking, thanks!

Geezz 3800 to 4200.... Well i know that 302 mustand engine..strong in 1st gear but a bit weak on the top end...I thought that engine was a roller 302 HO....age cometh to me. So find a donor 16 maybe 17..(19p nope)..Sorry bro umm yes install the 4 barrel it will keep you nose back in boat's and out of computer networking..:facepalm:

That is my 20' Gulfstream with the 5.0 roller cam. It wants to tear the transom out of the boat at any speed. Good thing the engine is bolted to the stringers. If I were to stuff that engine into the little BeachCraft, that thing would need wings or a snorkel.

Be that as it may, the original Gulfstream 302 (190 hp OMC) was identical to the 188 merc. Even the two outdrives had the same final gear ratio. That stock 302 was quite respectable in the 20' Gulfstream and I assume it will be a real screamer in that lighter, shorter, higher speed hull BeachCraft. That is probably why it suggests a higher pitch prop over the 15 x 17 in my OMC.

As far as the WOT spec of 3800-4200, that was true for both OEM motors. I regularly ran my stock Gulfstream motor up to 4800 and it never complained.

 

[Don S]

Re: Just looking, thanks!

As far as the WOT spec of 3800-4200, that was true for both OEM motors. I regularly ran my stock Gulfstream motor up to 4800 and it never complained.

What engine and year is that Gulfstream? Not a 1976 888 flat tappet engine in it, is it?
Don't compare apples to oranges and expect the same answer.

 

[Boomyal]

Re: Just looking, thanks!

What engine and year is that Gulfstream? Not a 1976 888 flat tappet engine in it, is it?
Don't compare apples to oranges and expect the same answer.

Don, I was speaking of the original flat tappet 190 hp OMC 302 in my 1975 20' Gulfstream. That is the one that would max out at 4800 with the 15 x 17 prop. In a wave of a midlife testosterone flare up, I changed that engine to a 2001 Ford Explorer 5.0 roller motor, removing the fuel injection, installing a '69 351w grind roller cam and a 600 cfm Holley 4 bbl marine carb. I still have the same prop on it as the stock motor. It is so scarey that I have yet to hold the throttle open on it.

The BeachCraft 888, that I was inquiring about the propeller for, is 100% stock.

 

[Boomyal]

Re: Just looking, thanks!

. Is this not the boat you posted a few yrs ago with the huge bow rail's?

Used to have huge bow rails.

 

[Tail_Gunner]

Re: Just looking, thanks!

Don, I was speaking of the original flat tappet 190 hp OMC 302 in my 1975 20' Gulfstream. That is the one that would max out at 4800 with the 15 x 17 prop. In a wave of a midlife testosterone flare up, I changed that engine to a 2001 Ford Explorer 5.0 roller motor, removing the fuel injection, installing a '69 351w grind roller cam and a 600 cfm Holley 4 bbl marine carb. I still have the same prop on it as the stock motor. It is so scarey that I have yet to hold the throttle open on it.

The BeachCraft 888, that I was inquiring about the propeller for, is 100% stock.

Ahh i see 50 more hp than a 3.0 yet 1.5 gearing..interesting and low rpm 3800 -4200 rpm....gotta be tourqe here and effeciency

http://www.iboats.com/AddPropToCart...ndor_id.699--viewcart.long--*******.129287846

There's a pick i dont believe a 4 blade would do much here you cant turn it to high enough rpm..LIFT. Walleyehed made that pick yrs ago big diameter low rpm heavy pusher type of prop. Now where's old marble eye's at a time like this...

 

[Tail_Gunner]

Re: Just looking, thanks!

Used to have huge bow rails.

Ahh now there is a old tub...Wanna race...

 

[Boomyal]

Re: Just looking, thanks!

I'll trade ya trailers. I hate those high roller trailers. As far as a race, that is an old promise that I would do some serious whoopin with that ol' tub! Even my Gulfstream would swamp you before you could overtake me.