Re: Doel-fins
John: Hmmm. Not so obvious me thinks. I have washers both above and below the cavitation plate; they are about a dime in diameter. They fit into a recess on the outside of the fin, i.e. do not contact the cavitation plate. Therefore, I cannot add bigger washers in this spot and adding extra ones would do NOTHING. The Doel-fin has a smooth flat surface that runs almost its entire length and this surface butts to the c-plate. Adding a washer between this surface (it's the only surface left) thereby creating a space betwen the plate and fin would increase stress both on the plate and on the fin.<br /><br />On the topic of lifting the boat with the motor instead of hull, I would suggest that some would argue this point with you, including me. Since the fin is supposed to run out of the water while on a plane (allowing you to increase the X-dimension), the hull is doing all the lifting and your point is moot. <br />During hole shot and below planing speeds, I would argue that the boat is not 'resting' on the fin instead of the hull but rather it allows the outboard to run in a more vertical attitude since the increased surface area of the fin cathes more water and applies more counteractive force. In other words, an outboard tries to runs vertically though water(which is most efficient since all thrust will be on the horizontal), but forces acting on the hull -whether it be gravity or water - push or pull the boat up or down and counteract this. An equilibrium is eventually achieved whereby the motor inevitabley is pointing in the non-vertical, i.e. pointing upwards during holeshot and downwards while on the plane. Increased surface area on the outboard catches more water, creates more of a counteracting force and thereby gives the driver more countrol over the attitude of the boat. <br />Paricularly during hole-shot with the motor trimmed in, I fail to see how smart tabs are advantageous.<br /><br />Once again, I restate my satisfaction with this type of device, as do dozens if not hundreds of others on this site. I get substantially improved hole shot, slower planing speeds and even slightly higher top end. All for less than $30. This is enough to offset the risk of spending signifcantly more $$$ for trim tabs for perhaps marginal improvement - or not. If you want to install a pair of tabs on my boat to prove to me how much better they are than a fin, we can make arrangements. If they show a marked improvement over my current set-up, I'll buy 'em. If not, you fill in and repaint the holes you drilled.<br /><br />This is starting to sound a little like the Amsoil posts.
