Originally Posted by Nos4r2
Search this site for doelfin(s) or doel fin and see what you come up with. There's a lot of + and - points to having them. I've had a bad experience with them but some love 'em...
General consensus (though never owned them) is that smart tabs are better though.
I mounted a 50 Johnson on my 4.7 Searider and ended up with Doel Fins which seem (to me) to have made an improvement in three areas.
1. I troll a lot at around 7 kts. and the fins make it easier to stay in that
groove without bogging down or running away.
2. The 50 was not the max hp spec for this boat and the fins seem to make
it easier to get up on a plane with a heavy load.
3. I do a lot of diving and the fins make for a real nice step when boarding
I don't monitor WOT speed and my guess is that the fins slow the boat to some degree, just my intuition. Performance flat out however remains just fine for me and in 1.5 to 2 meter seas I don't have the cajones to run flat out anyway...or possibly more accurately speaking, I wouldn't have any cajones left were I do do much of that in a 4.7 meter hull!
After nine years of hard use I can say one thing about the fins. They are durable. I am familiar with trim tabs but not familiar with smart tabs and will look for more info just out of curiosity. I've got this bug where I might upgrade to a 5.85 Ribcraft so I'm collecting information on all the details various systems to possibly maximize the set-up on a new boat. As posted elsewhere, the SeaRider after nine years is still tough as nails with no problems noted on either the tubes or the hull even with our brutal UV index down here!