The 42 in question may have been a non planning design and trim tabs would not add much at all, and would be a negative impact in a following sea and backing.
In a planning hull they can be invaluable, and are often installed from the factory. They allow you to modify your trim under way to suit sea and wind conditions without modifying your engine RPM's. Some believe a correctly designed boat does not need them, but I would not own a boat (planning hull) without them. Watch a boat go by with it's nose (bow) up in the air, so that the captain can has no view other than sky and his own boat. Adding more power may not do anything other than bring the nose even higher. It's either a bad design, weight distribution, running gear problem, or he does not know how to operate his vessel. Trim tabs would greatly help this boat. While on a plane, adjust your tabs before your throttles. Take them off (tabs up) and your rps go down, all on (tabs down) and the bow will bite and cause erratic steering and loss of rps. Max RPM's is a good starting point to leave them at. They need to be adjusted at each course change and any sea or wind changes. You can even steer the boat with them. Adjust for weight distribution when your crew hangs on one side of the boat etc. Take them off (up tabs) when backing or in a following sea where them can be very detrimental. Try backing with one tab down to see what it will do. Newer boats have them built into a well in the hull to help solve those problems. If you run your Uni as dispacement, you may want to take them off as they add drag and the other problems mentioned. You could try it by removing the tab portion and leave the piston to see how you like it. You should be able to take out the hinge pin on the tab. ( drive it out with a thin rod or coat hanger) Hope this helps. Thanks Rich Zimmerman 73 34' "Commitment" --- On Mon, 5/4/09, ron hammill <[email protected]> wrote: From: ron hammill <[email protected]> Subject: [UnifliteWorld] Re: Removing old bottom paint To: [email protected] Date: Monday, May 4, 2009, 10:25 AM #yiv639360679 #yiv1732366354 .hmmessage P { margin:0px;padding:0px;} #yiv639360679 #yiv1732366354 { font-size:10pt;font-family:Verdana;} i own 42 convertible and trim tabs help a lot > Date: Wed, 29 Apr 2009 10:03:19 -0700 > Subject: [UnifliteWorld] Re: Removing old bottom paint > From: [email protected] > To: [email protected] > > > Very thoughtful answer Rich, thanks. Confirms what I had been > thinking. I have a 40,000 lb twin turbo diesel 1973 42' and have > always thought the bottom paint weight might be a rounding error. The > only time I really see a difference in performance is when I run near > empty with fuel and water. (400gals and 170gals). Full diesel is > 2,500lbs while water is 1,500 lbs. The cummins have lots of torque and > turn big wheels. > > Heard a story once about a guy who installed trim tabs on a 42' and > they didn't do anything so he took them off. > > Bob S. > > "Rock 'N Roll" > > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "UnifliteWorld" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/UnifliteWorld?hl=en -~----------~----~----~----~------~----~------~--~---
