I’d like to put some Smart Tabs on my boat (KW1720cc), but apparently the swim platform is in the way. It’s only 1/4" thick. Can’t I just bolt through it to the transom? Does anyone have these installed on their 1720? I’d love to see some pics and hear your advice.
The other option is a hydrofoil, and I don’t want to drill into my motor.
The reason is severe porpoising from stern weight. It’s always porpoised to a degree. I installed my trolling motor last month and put the extra battery in the stern battery box because that’s where the wires terminated. The sea trial was fine… until this weekend with a full bait well and nobody sitting up front. I know, move the battery to the console. Well, I like my console storage for removable things, not batteries. $129 smart tabs seem like a good option. So show me what you got.
The Dolphin hydrofoil stopped mine from porpoising, but the motor now cavitates in turns. Is your cavitation plate on moter level with bottom of boat? Mine is a little higher but I figured Key West rigged them everyday and knew what to do.
Yeah, the cav plate is level, maybe an inch high. But that seems typical. It will cavitate in hard turns at high speed. If I go with a hydrofoil, it’ll be the SE Sport 300. But I don’t like the idea of drilling my motor.
I have a 1988 1720cc yhat did the same thing with a 90hp evinrude. Now have a 110 rude on a jackplate because it is long shaft. Still porpoises until I get an extra 100 or so pounds up front. Full tank and just my son and myself can only trim it back to just before the console. One of us sit on the front deck and it’ll trim back to the rear of console. Have the fin on the motor and it doesn’t help. I have a small hatch in floor just before front deck. Thought about adding water to compartment to see how much it will hold and if it will help. Need to redo the floor so I might try to push fuel tank forward about a foot. Don’t like idea of drilling holes in hull.
I thought the 1720 started in '92? Isn’t yours technically a 1700? Is that the same hull design? Your porpoising sounds worse than mine. I could live with it, I just don’t want to. Thanks for commenting though.
Have you visited their website? Or call them, they might have some mounting advice. I would think you’d do much better w/ SmarTabs than a hydrofoil because you can trim your motor properly. I have a hydrofoil and am also considering smart tabs, but not before a trolling motor
Yeah, i emailed them and sent them a picture of the problem area. Just trying to see if others already been down this road. The 1720 is a popular boat… certainly somebody else has put these smart tabs on.
Had it in 89.Took hull I’d to them trying to get info on fuel tank and they called it a 1720 and the dnr has it registered that way. Has a 42 gallon tank mounted below the floor under the console. Bow kind of flares a little. Hydrfoil doesn’t help me. Just need to figure how to add 120# forward while on the water but get rid of before putting back on trailer.
42 gallon tank!? Mine only has a 31 gallon tank. Too bad there wasn’t a way to block the back half of the tank keeping 21 gallons in the front portion. You’d probably be set then.
Gonna redo the floor soon and am thinking of making a spot for about 20 gallons of water if I can keep it centered. Thinking let it drain to the bilge and pump it out when getting close to landing or use a portable pump. I like the newer 1720’s over mine. It has a lot of wood in it.
before you make any changes like that, run the boat, and at WOT, with the motor trimmed just before the porpoise begins, look and see where the cavitation plate is running in the water.
it should be right at teh surface of the water
if its below the water, you need to raise the engine on the transom
to low will cause it to porpoise
Chris, yes I can see the cav-plate when running WOT. I ran it this weekend and with an empty livewell, I can trim the motor up a little bit without porpoising.
try a different prop before drilling holes for a hydrofoil or smart tabs. Had the same problem on a scout 162. went from a heavy cupped prop to a power tech SCD (semi cleaver stern lifter). The porposing drove me nuts and a guy on another site told me it was because the cupped prop had too much bow lift for the light bow. switched to the scd and problem fixed. SCD or a four blade provides more stern lift. Prop style of the SCD is like the white aluminum yamaha prop.
I don’t have a Key west 1720cc but I do have smart tabs. They really smooth the ride out. The little piston shocks they use aren’t saltwater tough though, mine rusted out in about 2 years. The company shipped me new one’s for free no questions asked, I hope it stays that way.
