Smart Tab SX on Diablo
 

With the positive experiences from several here I decided to put the Nauticus Smart Tabs on our 2001 Diablo wanted to share my experience.

The boat is a 2001 18' Diablo with a 140 hP 3.0 Mercruiser 2:1 drive running an aluminum 21" pitch prop. This prop leaves the boat feeling slightly underpowered but I like it when it's just my wife and I cruising around and maybe 3 of us towing a single tube. I put the original 19" prop on if we plan to tow multiple tubes and take some friends along. I've only run the tabs with the 21" so far.

I started with the 60lb actuators mounted per instructions and in the middle slot. No more wander at low speed and WOW up on plane much quicker with little bow rise. Big difference and really liked this as the 21" prop used to make it seem a little slow to get up on plane. Maybe capable of maintaining slightly lower on plane speeds but only by about 1 mph. There was still a little porpoise-ing when trimmed up but it seemed to correct itself on it's own or I only trimmed down slightly. I used to trim way down after bouncing over another wake. Top speed seemed about the same but our boat is not very fast in the first place. Speed at our normal cruising seemed about the same, 3000 rpm = almost 25 mph. WOT we might hit 38-39. All my speeds are GPS numbers and speed indicated on my speedo is just a tiny bit optimistic but very close.

Then I tried the tabs at full strength, 1st slot. On plane a little better but you could almost feel the extra drag. Not much need for the motor trim anymore and when I trimmed up just a little too far I felt strong cavitation come on suddenly like never before. Some porpoise action still present even at full strength but normal cruising of 3000 rpm dropped to about 24 mph. Not a big deal but it did feel heavier all around.

Now I tried the lowest setting. More bow rise and slower onto plane which is suddenly a BIG disappointment. More porpoise was back but trimming the motor allowed me to get just over 25 mph at 3000 rpm. A WOT run let me see close to 40 mph but that's about the limit of our little boat. With this prop rpm is a little lower than it should be, maybe 4300 and with the 19" I remember closer to 4800 but never more than about that same speed.

I noticed my anode skeg is not adjusted quite right since the last work I did included a new raw water pump and Smart Tab install and now some left steer was always needed to go straight. I did not think to have a socket along (oops) to fix that but will next time. So I put the tabs back midway for now and just very happy with the overall performance and attitude of the boat even if maybe WOT top speed is off slightly. I don't run WOT much and prefer to cruise along at lower rpm and have a more quiet leisurely ride which I why I go to the lake in the first place.

Next trip I'll get the little skeg right and maybe try in between the middle and softest set point.

Well worth the roughly $100 for this little Diablo. I would not hesitate to put them on the smaller Mariah hull designs.

http://www.mariahownersclub.com/foru...g-img_3810.jpg

Re: Smart Tab SX on Diablo
 

My 180 Diablo has the V6 and when I first got her she suffered from having a "fat arse"
I really had to punch the throttle, fully trimmed in to get over the hump.

The Smart tabs are the best thing you can do for a Sub 21' Mariah. :wink_thumbup:

As for the trim tab, just get your self a flat one. Saves all that fiddling :yes_grin:

Re: Smart Tab SX on Diablo
 

I have the 182 w the V6 w the 60# SX tabs...did a few trials as you did and came with the same results...have them set on the 2nd setting now (between the softest and the middle) and she runs great! As mentioned, best 100$ spent...drives like a new boat...liked them so much we added them to a friends 3.0L 16ft boat which would take 2 football fields to get on plane...we recently get that down dramastically and came to find out shes only running on 3 cyl...LOL

Re: Smart Tab SX on Diablo
 

4300 rpm is working your engine too hard. Put that 19 back on the boat and then make adjustments. You need to be close to 4800 @WOT. I'm betting you'll be a lot happier with the results.

Re: Smart Tab SX on Diablo
 

I hear that and I know if I have a full load I need the 19". It is back on for our next trip that includes a family with 3 small kids. I know I used to see 4400, almost 4500 with the 21" which is fine for WOT. The 19" would let it get close to 5000 way back (which is over really) but I have not run it in a couple years. I think the tach may be sticking slightly as I've had trouble with it a few times and had to fiddle with it. I can also put a scope meter on the tach signal to get a really accurate engine speed if I need to.

When I ruined my original 19" late one fall I found such great deals over the winter I bought the replacement 19 and the 21 to try (about $40 each new if you can believe that), and honestly the boat just feels better with the 21 IF it is just two of us riding. With the Smart Tabs now it just seems to effortlessly get up on plain and cruise so nice at just about 3000 rpm which is where we do the bulk of our running. I think trimming the motor down probably places more load on it than the prop change. I really don't know though as there is no way to measure motor load other than WOT test.

Next trip we'll see how it feels and get numbers.

Thanks