Trim... Tilt.....Whale-tail..........Prop

[mutron77]

Hello,<br /><br />I need some education in a certain area. I have a 17 foot chriscraft runnabout, '85 90 horse EV. Power Tilt, trim and whale tale.<br />My areas of ignorance:<br />What exactly does the whale-tail do????<br />What am I looking for in adjusting the power trim when running.<br />What type of props are available and why should I care?<br />I guess I need an overview on how these factors affect performance.<br />let 'er rip...............<br /><br />H90

 

[andrewkafp]

Re: Trim... Tilt.....Whale-tail..........Prop

http://cavity.ce.utexas.edu/~kinnas/uti99/node2.html <br />Hydrofoil (Whaletail) is supposed to provide stern lift and help with cavitation.

 

[TPD211]

Re: Trim... Tilt.....Whale-tail..........Prop

I'll take a stab at it. I'm fairly new to boating but have asked or read the same questions also.<br />.....What exactly does the whale-tail do????<br />The whale tail will allow you to trim the bow down at lower speeds and can also help in turning. I recently installed a whale tail on my 88 Spl on my deckboat. It made a world of difference in planing at lower speeds.<br />.....What am I looking for in adjusting the power trim when running?<br />As I understand it, you want to trim the bow down depending on the speed your running and to your preference. A trimmed out boat will have better MPG I understand.<br />.....What type of props are available and why should I care?<br />There are 3 and 4 blade props that are stainless steel or aluminum metal. The prop you use depends on how you use the boat. You want to use a prop that allows the motor to turn the proper RPM's at wide open throttle (WOT), if not, you take the chance of lugging the engine and possible engine damage.<br />All this I learned from these forums, correct me if I'm wrong guys, I'm still learning.

 

[Chris1956]

Re: Trim... Tilt.....Whale-tail..........Prop

Horse90, Trim is designed to either give the greatest economy (and as a byproduct greatest speed), or a smooth ride in rough water. When you trim out (or up) the bow rises, and when you trim in (or down) the bow falls.<br /><br />So to gain greatest economy, trim out (or up)(while adjusting your speed to your preference) until either the motor starts to ventilate or the boat starts to bounce (porpoise)on its own. To get the smoothest ride, trim in (or down) until the ride is smooth. Usually just before the bow starts to plow water.

 

[Jdeagro]

Re: Trim... Tilt.....Whale-tail..........Prop

Some of these questions can be answered in our tech report on Boat performance and Balance.<br /><br />If you would like one at no charge e-mail your address to John@nauticusinc.com<br /><br />You need to run the boat first with nothing, then deside what you would like to make better.