[Aussie]

Hi All, New to the club and this whole forum thing.Just bought an RX181 with a 3.4 mecruiser 190hp. been out twice. Great with one skier but lacks a bit of punch with two single skiers. Has a 19" pitch 3 blade prop, what prop would be best for more initial grunt? Karen, NSW Australia

[WetWilly]

Ahoy Karen and welcome to the forum!

You can try dropping down to a 17" or 16" Pitch prop and that will give you about 400 to 600 more rpm on the start but be extremely careful not to over rev the motor at top speed. keep with an aluminum prop since they're softer than the steel props so they tend to de-pitch just a little during the takeoff giving you even less pitch on the start.

Unfortunately, at 3.4 liters, there just isn't enough motor to get a whole lot more "punch", so you will need to experiment to find an acceptable compromise.

BTW, we have a few other members from Aussie land, have a look at our Members Map and while there, go ahead and stick your pin on it as well.

Good luck,
WetWilly

[Aussie]

Thanks Wet Willy, Karen

[mikeyt]

hi Karen

Are you sure your motor is a 3.4 and not a 4.3? Either way, hauling two skiers around behind an 18' boat with the 6 banger is asking a lot of your boat/motor. Dropping the pitch of your prop down 2 or 3" can have some serious effects on your performance & life of your motor if not done correctly. Some questions you need to ask before making the change are: What is the top speed of your boat and at what rpms do you reach top speed? Also, what type of performance do you want? Your 4.3 has a recommended range of 4400-4800 rpms at WOT (Wide Open Throttle) and your best performance is when you get your WOT rpms within 100 of the max. So, if your 19" prop is turning 4800 rpms at WOT you are at or near perfection. Dropping to a 17" will put you well over the high end of the range and will knock 3-5mph off your top speed. Going further than than (say a 16") will take you up to about 5400-5500 at WOT and seriously affect your performance & engine life. You need to understand that no matter what prop you install you cannot achieve maximum low end 'grunt' and high top speed at the same time. The 19" prop was installed by the mfr. as the best compromise. You can improve things however if you are looking to improve your towing capacity and aren't too worried about hitting maximum top speed by installing a 4 blade prop but again you want to stay within the recommended rpm range at WOT. And, not all 19" props (whether they're 3, 4 or 5 blade) provide the same performance so its best that we know the baseline performance of your boat before making any changes.

Also, another thing you could consider is the installation of 'Smart Tabs'. A number of our members have installed them (including a couple of our Aussies who have similar boats to yours) and all report that the boat planes faster, stays on plane faster and provides improved performance. The Smart Tabs will provide some extra stern lift and allow you to trim out the motor a little more when starting out which should allow you to get the skiers up out of the water faster. The Smart Tabs are a relatively easy install (a couple of hours and some patience should do it) and for under $200 are an inexpensive improvement in the performance of your boat.

[Aussie]

Thanks Mikey,allot of useful info, you are right it is a 4.3 I will check out all the speeds and revs etc. Could you please give me some more info on Smart Tabs, I haven't heard of these. Thanking you, Karen.wink_thumbup:

[mikeyt]

Originally Posted by Aussie

Thanks Mikey,allot of useful info, you are right it is a 4.3 I will check out all the speeds and revs etc. Could you please give me some more info on Smart Tabs, I haven't heard of these. Thanking you, Karen.wink_thumbup:

Hi Karen

You can read about the Smart Tabs via the Nauticus website here
Hopefully, one of our Aussie members "Dudders" (over in Perth) can chime in with his thoughts on the Smart Tabs & their benefits as well as ordering them into Oz. Also, do a search on our site for "Smart Tabs" and you will find lots of useful information.