Okay... not what I expected! Nauticus trim tabs work great but I lost some speed!

[rhillman75]

I had a 14-3/4 diameter 3 blade 19 pitch prop that had some age on it (used as back up). My wife decided to "smoke" my 14-3/4 4 blade 19 pitch prop 4 weeks ago in shallow water. The planing with the 4 blade was better (I knew that from comparison), but I decided to buy a 14-7/8 3 blade 17 pitch prop from iBoats that seem to gain a little more MPH (maybe 40 tops) at 4,800 rpm with maybe 50 pounds of gear, 2 adults @ 300 pounds, 2 kids @ 100 pounds. I usually run about 3/4 throttle to keep the RPM down to 4000-4200, but I am losing MPH by doing so. I put the trim tabs on (SX 60 Series) and they did make a huge difference in planing and porpoising but it seem to lower my MPH with them in the stock hole number "3" setting. I know I'm about at max on RPM with this set up but I can still only get about 32 MPH on the GPS. I guess I really do not know where to go from here. The motor is timed, idle set at 700 RPM, ANYTHING and EVERYTHING has been done as far as maintenance... did I get the wrong prop? The boat is a Sylvan V196 (Barritz... I think), with a Mercruiser 4.3LX Gen + motor and the Alpha One outdrive. I keep hearing of "bigger" boats (length wise) with the same motor that get upwards of 40+ MPH. With that said... what should I do? I did not play with the trim tab setting because I did not have time in the water, but I do not think adjusting them is really going to obtain more MPH (but then again... I do not know). According to the manual I am at 180 H.P. with a gear ratio of 1.81:1 and WOT RPM of 4400-4800. Is going above a 19 pitch going to be any better? Any thoughts would be great!

 

[craze1cars]

Re: Okay... not what I expected! Nauticus trim tabs work great but I lost some speed

Just to clarify if I'm understanding you correctly:

40 mph before adding Smart Tabs. 32 mph with same prop, after adding Smart Tabs and changing nothing else.

Is this correct? If yes, then your problem is in the Smart Tabs. Contact Nauticus. They have excellent customer service and will help you thru what needs to be done. Either you installed them incorrectly, or you have them set at the incorrect hole, or they sent you cylinders/shocks that are too strong for your boat and they will exchange them out for weaker ones for free.

Basically it sounds to me like your Smart Tabs are not leveling out after you get on plane, as they are supposed to do. Therefore they are acting like a brake creating huge resistance while dragging thru the water. Only you can figure out why this is happening...but I suggest you enlist Nauticus's support in helping you figure out why and how to correct it.

 

[Maclin]

Re: Okay... not what I expected! Nauticus trim tabs work great but I lost some speed

What he (craze1cars) said....

If you go onto the Nauticus website and read how to tune the tabs you will see that the end result should be the same or slightly higher top speed.

 

[Tail_Gunner]

Re: Okay... not what I expected! Nauticus trim tabs work great but I lost some speed

Take a picture of a frontal and side view...Something is wrong

 

[ufm82]

Re: Okay... not what I expected! Nauticus trim tabs work great but I lost some speed

Since you said you have not tried adjusting the tabs yet I wouldn't be too distraught over the speed loss. Move the rams as instructed per the Nauticus page before going deeper into the funk. When I first installed my Smart Tabs I also lost speed. By gradual changes I found that my set-up works best with the rams in the "lightest" position. (I have the 90lb rams.) By using the string deal I found that the tabs were even with my hull at speed and that is where they are supposed to be at WOT. And I picked up 2 mph with them as they help lift the stern up, getting even more of the boat out of the water.
Do the adjustments first and go from there.