JoLin
Vice Admiral
- Joined
- Aug 18, 2007
- Messages
- 5,146
My boat is a 21? pro-line w/a cuddy, constant deadrise (20 deg with no aft planning surface) deep-v with a stern-heavy configuration. I had already swapped my 3-blade aluminum prop for a 4-blade stainless (Solas Titan) with excellent results. I had a top speed of 39+ mph and prop slip of 12%. I was hopeful that Smart Tabs would correct my remaining problems with inadequate stern lift, slowness to plane, and generally mediocre handling at cruising speed.
After an email conversation with John @ Nauticus, I ordered a set of ST1290-80 tabs fromn iboats. I had a concern based on some other reports on this forum, that the 80-pound actuators might be too stiff. John felt I needed the 80-pounders, and assured me that I could swap them for 60-pounders if necessary for the cost of shipping. I thought that was a pretty fair deal
I installed the set with the tab bracket set to the center position, and the transom bracket also set to the center of the ?slot.? Tab angle was set to 25 degrees. Initial results were simply amazing. The boat literally jumped on plane within a couple of seconds with almost no bow lift. Very impressive, but at speed the tabs were exerting too much downward pressure on the bow, and I lost 2 mph in top speed (to 37 mph).
I pulled the boat out of the water and adjusted the actuators to the next softer setting, and readjusted the transom bracket to maintain the same 25 deg. angle on the tabs. Generally better results all around. There was a small increase in bow lift and time to plane, but at cruise speed the boat rode level and sure-footed, and I picked up about 1 mph over the initial setting (to 38 mph).
I was still looking for the advertised increase in top speed along with the other improvements, so I pulled the boat again and adjusted to the softest setting. I also adjusted the transom bracket once again to maintain the 25 deg. angle. This attempt was not so successful. Bow lift and time to plane both increased again, and I was running bow-high at cruise. Basically, the same problems (tho to a slightly lesser degree) that I had before I installed the tabs. And my wot speed actually DECREASED to 36 mph.
After some head scratching, I theorized that at the softest setting the tabs were simply adding drag without adding enough lift to positively influence the boat?s attitude. That resulted in a loss of performance all around. I'm no engineer and can't be positive of my theory, but it sounded good to me
I decided to put the actuators back to the setting that had given me the best results previously (second softest). This time I decreased tab angle by a couple of degrees, thinking this might finally yield the balance of boat attitude and speed I was looking for. Unfortunately the bay was a bit rough today and I couldn?t really open her up. I?ll try again tomorrow if possible, but then I?m leaving town for a week. If my top speed remains below the 39 mph I had before tabs, I?ll contact Nauticus and pick their brains about maybe starting over with 60-lb. actuators.
I think that somewhere there?s an actuator strength and tab angle that will do what I need, but it?s been a pain. I?ve had to winch that heavy mutha out of the water 5 times over the last 2 days, and I?m no spring chicken (my back and shoulders are pretty sore). I?ve spent hours launching, retrieving, adjusting and testing the tabs, and about $100. worth of fuel. At some point I may get them set up right, but if I was to do it over again I?d invest the time and money I've spent, in a set of adjustable tabs like Insta-Trims. I'm not complaining. Smart Tabs are a very clever idea, and I think Nauticus customer support is excellent, but you get what you pay for, and they aren?t necessarily for every boat.
After an email conversation with John @ Nauticus, I ordered a set of ST1290-80 tabs fromn iboats. I had a concern based on some other reports on this forum, that the 80-pound actuators might be too stiff. John felt I needed the 80-pounders, and assured me that I could swap them for 60-pounders if necessary for the cost of shipping. I thought that was a pretty fair deal
I installed the set with the tab bracket set to the center position, and the transom bracket also set to the center of the ?slot.? Tab angle was set to 25 degrees. Initial results were simply amazing. The boat literally jumped on plane within a couple of seconds with almost no bow lift. Very impressive, but at speed the tabs were exerting too much downward pressure on the bow, and I lost 2 mph in top speed (to 37 mph).
I pulled the boat out of the water and adjusted the actuators to the next softer setting, and readjusted the transom bracket to maintain the same 25 deg. angle on the tabs. Generally better results all around. There was a small increase in bow lift and time to plane, but at cruise speed the boat rode level and sure-footed, and I picked up about 1 mph over the initial setting (to 38 mph).
I was still looking for the advertised increase in top speed along with the other improvements, so I pulled the boat again and adjusted to the softest setting. I also adjusted the transom bracket once again to maintain the 25 deg. angle. This attempt was not so successful. Bow lift and time to plane both increased again, and I was running bow-high at cruise. Basically, the same problems (tho to a slightly lesser degree) that I had before I installed the tabs. And my wot speed actually DECREASED to 36 mph.
After some head scratching, I theorized that at the softest setting the tabs were simply adding drag without adding enough lift to positively influence the boat?s attitude. That resulted in a loss of performance all around. I'm no engineer and can't be positive of my theory, but it sounded good to me
I decided to put the actuators back to the setting that had given me the best results previously (second softest). This time I decreased tab angle by a couple of degrees, thinking this might finally yield the balance of boat attitude and speed I was looking for. Unfortunately the bay was a bit rough today and I couldn?t really open her up. I?ll try again tomorrow if possible, but then I?m leaving town for a week. If my top speed remains below the 39 mph I had before tabs, I?ll contact Nauticus and pick their brains about maybe starting over with 60-lb. actuators.
I think that somewhere there?s an actuator strength and tab angle that will do what I need, but it?s been a pain. I?ve had to winch that heavy mutha out of the water 5 times over the last 2 days, and I?m no spring chicken (my back and shoulders are pretty sore). I?ve spent hours launching, retrieving, adjusting and testing the tabs, and about $100. worth of fuel. At some point I may get them set up right, but if I was to do it over again I?d invest the time and money I've spent, in a set of adjustable tabs like Insta-Trims. I'm not complaining. Smart Tabs are a very clever idea, and I think Nauticus customer support is excellent, but you get what you pay for, and they aren?t necessarily for every boat.
