Re: Prop hell. 70 HP Evinrude 2 sroke 3cyl.
I must have paid my dues since I am being invited into a prop thread. <br /><br />There is no question that you will need to choose the correct size and pitch prop for the application. Making sure the tach is accurate is a given. There is also no question that one prop style verses another will give you different performance. But there is a big However.<br /><br />Not all performance problems can be solved with the prop. Not all boat hull designs provide the same handling characteristics. <br /><br />And, I having been talking to some "overworked props" and they feel they are asked to work to hard and do too much, and if they don't do what is expected they get thrown in the back of the garage, and treated like trash, while the hull just does as it pleases! Ok, I'm over the top, but it is Friday. <br /><br />Trim Tabs are like wing flaps on an airplane, they adjust the shape (design) of the hull to increase the performance "window size" so that the efficiency of the boat has a broader range. <br /><br />Most boat manufacturers of smaller boats (under 22 feet), their Dealers, and boaters say that if the boat need trim tabs there is something wrong with the hull. Well, I would agree! There is something wrong with nearly every boat hull. They have a fixed design. And. unless the boat is designed for a very specific function (exp.: drag boat or barge) this design will work well under one set of conditions (load, speed, water, etc.) and deteriorate in other conditions.<br /><br />Boat balance & design mean as much to performance and handling as the HP and prop. I.e.: you will never ski behind a barge!<br /><br />All of that said; Trim Tabs give you the ability to change the boat shape and thereby improve or expand the window of performance. Because of this the prop can now be used for it's primary purpose - propelling! <br /><br />Believe me when I say that no "prop" I have ever talked to, has objected to a some help, and less work. I am telling you that if you guys don't stop giving them too much work, there is a revolution in the works! Oops There I go again.<br /><br />Smart Tabs are specifically designed for smaller (9' to 22') boats from two view points, price and ease of use. They start off deployed, then as the water pressure increases, they retract up (at planing speeds). When in the up position they act like a suspension system to control the ride and handling ( Porpoisiing, chine walking, etc.) just like your car. Since the system is constantly active they help keep the boat at its best efficiency. The system is also adjustable to the specific boat. Once the adjustment is done, its drive and go. Nothing else to do.<br /><br />The results are minimal bow rise, faster acceleration, easier planing, better ride, no porpoising, and more top speed. Guaranteed! <br />One last note, the tabs will keep the bow down on acceleration, but if properly adjusted they will also increase the rpm's at WOT. Sooo, if you are running high now you will run even higher with the tabs. My advise: Make sure the tach is good, put Smart Tabs on (what did you think I would say?), then choose the correct prop to get the rpm's correct. You need to make the boat hull efficient first, then prop. Ask Lube Dude!
