The prop spec's are usually stamped on the hub, around where the prop nut is. It will either specify the dimensions (i.e. 14x19p) or it will list a part number (48-######A##) which you search for on the Merc site to obtain the specifics.

Hi Guys,

Thanks again for the info, the boatyard checked the prop this morning and said it is a 19 pitch, they measured from the centre of the shaft to the outside edge of the blade and it was 13 1/2" the number on the prop was 48 832 830 A45, is this the standard prop for a Mariah 182 3 litre? should l move up to a 14" 19P for a little more top end speed will the engine and leg be ok with this?

Cheers,

Gary

Hi Gary

It's the increase in pitch (not diameter) that will provide a higher top end. Note though, that it may make your boat a little sluggish out of the hole. Increasing the pitch will also lower your rpm's at WOT. You may find that the 19" pitch gives you your best compromise.

I used to have a 1996 Crownline 175 Bowrider with a 3L 4-cylinder and Alpha drive. It came with a 19P 3-blade aluminum prop and after break in, I noticed it ran at or or just slightly above the maximum RPMs of the allowable range. I bought a 21P aluminum 3-blade prop and she ran a little faster at WOT with a few less RPMs. Either prop was basically OK, the 19 was good for heavy loads and water sports, and the 21P was just fine for cruising with my First Mate and small child. I expect that you could use either on your Mariah.

The 3-blade Mercruiser props seem to come in odd pitches only. I started looking at 4-blade props and found they run in even pitches. Everybody now knows that I run a 20P 4-blade aluminum prop on my Z210 with a 5.7LX and Alpha drive. It is kind of like my poor man's High Five for water sports and hole shots. For cruising on rock-free lakes (like southern Lake Michigan) I mount up the 3- blade stainless steel 21P Vengeance for maximum cruising efficiency and top end.

Best regards,

Hey Border1010...I have an aluminum 4-blade 18P prop with Smart Tabs and you are right about the wake not being very big. But the performance between the 4-blade keeping a constant lower speed and the Tabs planing my boat out quickly....I can't complain.

When I want a bigger wake......I usually shorten my wakeboard rope appx 15', and wow what a difference. My rope has three sections, which I will go down one section (which is probably 15-25'). Makes a difference. As far a hydrofoil......I used one and it helped out as well, but the tabs give me a smoother ride across the lake in general.

So everything I have read here, I must have a problem... New to boating so be easy with me.. I have a 4.3 with a alpha 1, 3 blade 19 pitch and a rpm of 5300... I sounds like my rpm is way to high???? boat will run about 50 mph and pull 2 skiers... but if I pull a wake or knee boards of the heaver side its hard to keep a constint rpm... help!!!!

I think that is a good problem to have! The lakes around you are probably at about 400ft above sea level which helps the engine run stronger(better air), you could probably stand to go to a 21p prop and will pick up another 5 or so MPH and drop your rpm to about 4800. You will lose some bite out of the hole, if that is real important to you check into a 4 blade prop. I would go to a local prop shop that will let you test different props until you find the one that you like the best. That is assuming your Tach is set to a 6 cylinder engine, may want to check that on the back of the tach.

I will check the tach tonight.. I didnt think anything about the rpm I thought it was in range cars are about 5500 with that engine so I thought I was ok... I dont want to hurt the little thing you know!!! I think I can try props in Havasue thanks for the info...

I have a 4.3 alpha 1 20 foot shabah. I am running a ss 3 blade turbo prop. Not really sure of the pitch, I will have to look tonight. I run wot at about 5400 rpm and about 58 mph. I have a hydofoil on the lower unit, no smart tabs. My hole shot is great and I plane out very quick. Not really looking for more on the top end but I sure don't want to damage the engine with the high rpm. Any comments for me? I can always stay out of throttle to keep my rpms down but that is kind of hard to do.