southrabbit Posted October 11, 2013 Share Posted October 11, 2013 6.5m glass boat 150hp outboard goes great in straight light. however when turning at speed when towing tube it seams like engine is not low enough in the water. how low should engine sit in relation to transom Link to comment Share on other sites More sharing options...
tasksta Posted October 11, 2013 Share Posted October 11, 2013 I had the same problem and had to lower the outboard one hole. Something about the cav plate lining up with the hull. Link to comment Share on other sites More sharing options...
Guest Aussie007 Posted October 11, 2013 Share Posted October 11, 2013 6.5m glass boat 150hp outboard goes great in straight light. however when turning at speed when towing tube it seams like engine is not low enough in the water. how low should engine sit in relation to transom sounds like your getting cavitation when turning try not to turn so sharp or try tow at a slightly slower speed Link to comment Share on other sites More sharing options...
Geoff Posted October 11, 2013 Share Posted October 11, 2013 The top of the cavitation plate should be level with the bottom of the transom. If still a problem drop it a few mm more. If after that you are still getting cavitation do as Gazza suggests , not to turn too sharp or , you could fit a Permatrim. Geoff Link to comment Share on other sites More sharing options...
oz_brett Posted October 11, 2013 Share Posted October 11, 2013 Yep once again cavitation plate in line with bottom of transom if this is already in line or before making any other changes try trimming the motor in. what I do to get the trim at the best setting is move steering wheel back & forth feeling the force it takes to turn the wheel at the same time adjust trim in or out until force to steering wheel is equal from left to right. This setting is good for travelling strait & light turns but for quick or sharp turns trim in just before turning then back out again as you come out of turn. Brett Link to comment Share on other sites More sharing options...
southrabbit Posted October 15, 2013 Author Share Posted October 15, 2013 Thanks, where is the transom and what is a cavitation plate.. only joking thanks fellow boaties. back to dealer and he can drop it at next service. Link to comment Share on other sites More sharing options...
spaners Posted October 15, 2013 Share Posted October 15, 2013 Tilt motor down on tight turns,tilt it back up on the straight. Link to comment Share on other sites More sharing options...
BWV Posted October 16, 2013 Share Posted October 16, 2013 Southrabbit, Your ventilation when turning or towing sounds like you have the wrong prop. Guys sorry to say but everyone that has said the Cavitation plate, its actually an anti-ventilation plate (AV) should sit level with the bottom of the transom are wrong. If its level its to low! a rule of thumb that works pretty well is that for every 30cms your shaft is back off the transom your AV plate should sit 3cm higher than your transom. 95% if not more of all boats come out with the engines mounted to low. There is another thread on the forum about engine height which would be well worth a read, here it is: http://www.fishraider.com.au/Invision/index.php?showtopic=61038&hl=%2Bengine+%2Bheight#entry429676 I have lifted the engines on all my boats and I have had an awful lot! by having the correct engine heath and prop will increase performance and fuel efficiency of the boat . Trimming it up and down all the time will work but its only treating the symptom not the cause. Some people swear by the "permatrim" but if your set up correctly there is no need for one as it will be clear of the water when on the plane and it wont work. I'll need some more info off you to steer you in the right direction What's your RPM at WOT? Manufactures RPM range for your outboard? What size of prop are you running and number of blades? 4 blades like run a lot higher than 3 blades What is WOT speed when trimmed correctly? Can you take a photo of your AV plate when running on the plane and trimmed correctly? you should be able to see it on top of the water level if you cant your too low! Link to comment Share on other sites More sharing options...
oz_brett Posted October 16, 2013 Share Posted October 16, 2013 don't know about you Southrabbit but I learnt something from all that,Thanks Whaler 255 :-) Brett Link to comment Share on other sites More sharing options...
Frantic Posted October 16, 2013 Share Posted October 16, 2013 use ya trim mate Link to comment Share on other sites More sharing options...
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