[wsl]

I purchased a Shabah model 181/0 with a mercruise 4.3 LX/V6 Alpha One. We like to pull multiple skiers and boarders. I would like to get the max power and the quickest start. The top end speed does not need to be that fast. What would be the best pitch and size?

[mikeyt]

I would start with a 19" pitch 3 blade aluminum or SS prop or a 20" pitch 4 blade SS prop for what you want. Either of those props will give good low & mid range acceleration. I dont know about pulling multiple skiiers or boarders at once though with a 4.3L.

[wsl]

I do not know the pitdh or diameter of our current prop, however the top speed is 55+. Would the props you suggested lower the top speed?

[mikeyt]

I would be extremely surprised if you are actually hitting 55+ with a 180/4.3L combination. It may be the speedo says that but that is very optimistic. You should check it with a hand held GPS sometime. 50-51mph is about what can be expected.

If you remove the existing prop it the diam & pitch will be stamped in the inside of the hub. Given what most others here run on their 180/4.3L combos, either of the 2 props i suggested will lower your top end but provide more low-mid range acceleration. With props the general rule of thumb is:

Higher pitch = higher top end, less responsive low/mid range & lower rpms
Lower pitch = lower top end, more responsive low/mid range & higher rpms.
4 blade props (& even 5 blade props) have more 'bite' than a 3 blade but also cause more drag in the water so there is always a trade off somewhere.

Your 4.3L needs to stay somewhere between 4400-4800 rpms at WOT per Mercruisers recommendation. But for practical purposes if you are hitting 4900 or even 5000 it wont hurt anything unless you run at WOT for longer periods of time. Higher rpms cause higher fuel usage & faster wear & tear. Going below the range causes the engine to 'lug' and be overworked.

[Dredd]

I have an aluminum 19" 3-blade in good shape but it needs a diffuser ring (~$15 installed). PM me if you're interested.