Smart Tab size selection

[rook]

I'd like to put Smart Tabs on a 21 ft. Bayliner Capri with a 120hp Volvo Penta drive, do I need the 60 or 80 lb model. The boat right now will not stay on plane under about 3300 rpms , will I see a significant performance difference? I get about 30 mph at 4500rpms now, will I gain top end or not, just curious. Thanks alot I appreciate any input.<br /><br />Sean

 

[vipzach]

Re: Smart Tab size selection

That speed seems kinda low for 4500 rpms. I don't know wich tabs you need, but nautijohn will probly come around and help with that. From what I have read and heard on here you will gain some top end speed. I have an 18ft VIP that runs about 40MPH at 4500 rpms. What size prop do you have? Maybe I am wrong, but that speed/rpm seems off.

 

[stevens]

Re: Smart Tab size selection

I have a 21' daycruiser with a 120 hp inboard turbodiesel and an Alpha drive. NautiJohn recommended the 1290-80 for my boat, and this has proved to work out really well.<br /><br />Although our boats & engines may be different, I can assure you that you will see a significant improvement in bow rise (mine went from 17 to 10 degrees) and planing speed (for me: from 15 to 11 knots). I didn't see much improvement in top end speed, but many people do as they get a more stable ride and can trim the drive out further than before.<br /><br />I agree that your boat seems a bit slow for that rpm. How are you measuring the speed, with a GPS?<br /><br />With a 23" prop I get 41 mph at 4100 rpm, but my diesel engine probably has more torque than your gas engine to turn this pitch of prop.<br /><br />Overall, the boat just handles better and smoother with the tabs, and the "shock absorbing qualities" are unlike all other tabs.