Guest DavidG Posted January 28, 2019 Report Share Posted January 28, 2019 New owner of a 2018 Hewes 18 redfisher with the Yamaha 115F, ,jack plate, trim tabs, power pole mounted on Right rear of transom, Minn Kota mounted on left side of bow. Garmin transducer mounted in cavity right side of drain plug by a few inches. Less then 6 hours on motor. The boat comes out of the hole quickly and comes up on plane easily but as soon as you hit or even think about hitting the trim up switch, the prop starts cavitating and the RPM rises as the boat slows until the Rev limit kicks in.Full tank with 2 people in it. Has the factory 3 blade prop which they’ve allready had to repack? ( never heard of this before) on the trailer you can actually feel free play side to side on the prop. 6 weeks of owning which the past 3 weeks have been in the shop. I’ve always owned larger Deep Vs so this is new to me. Does anyone have any ideas? Thanks all! Link to comment Share on other sites More sharing options...
geeviam Posted January 28, 2019 Report Share Posted January 28, 2019 First thought is maybe the transducer being so close to the keel and directly in front of the prop blades, would cause too much turbulence for the prop to stay hooked up. Motor height is another concern. What size jack plate? Are your motor mount bolts in the top hole? Which "factory" 3-blade prop are you using? Yamaha Talon SS? Link to comment Share on other sites More sharing options...
BrownBear Posted January 28, 2019 Report Share Posted January 28, 2019 7 hours ago, DavidG said: ...on the trailer you can actually feel free play side to side on the prop.... That's totally outa whack. My transducer is mounted on the transom between the well and the tabs, right in line with that strake or rib running under the hull. No issues, even though it's a biggun. I have a 4-blade and I can make mine cavitate with the jackplate all the way up and the trim tabs down a lot. Kinda developed a "feel" for it on starts in real shallow water, stopping the throttle just short of cavitation and once on step, raising the tabs and maybe dropping the jackplate a little. But go to full throttle before raising the tabs and it's instant cavitation. Link to comment Share on other sites More sharing options...
HoneyB Posted January 28, 2019 Report Share Posted January 28, 2019 First thing i would do is inpect that prop. is it a pressed in hub or a slide in sleve? also spin the prop by hand and look for run out on the prop shaft. your motor could have been damaged before or during the instal. I do not think a slightly bent propshaft would cause the cavitation that sounds like your motor may be running to high. can you post some pics from the back of the boat of the motor set up? Link to comment Share on other sites More sharing options...
lurem Posted January 28, 2019 Report Share Posted January 28, 2019 You have had it 6 weeks and it has been in the shop 3 weeks? WOW! can you explain more. Link to comment Share on other sites More sharing options...
mulligan Posted January 28, 2019 Report Share Posted January 28, 2019 You should not have any side play in the prop, a little front to back is normal. You may just have a bad hub. Like Geevian asked knowing the prop type would help as some do not like much trim before there is cavitation. I would hope with a new boat the dealer would get you straightened out. Link to comment Share on other sites More sharing options...
NCTribute Posted January 28, 2019 Report Share Posted January 28, 2019 Sounds more like the prop is spinning on the hub, my guess is who ever pressed in the hub did not know what they were doing or used the wrong hub. I would try a different prop and see if you still have the issue, at least narrow it down to a prop or engine issue. A bent shaft would be causing some nasty vibrations when on the rev limiter. Link to comment Share on other sites More sharing options...
Guest DavidG Posted January 28, 2019 Report Share Posted January 28, 2019 The prop has a slide in rubber bushing, I’ll get the prop type and size and pitch on it today. I’m thankful the dealer has been working on it but it’s been in the shop now for 3 weeks out of 6 weeks of owning it. Living in North Florida, the fishing days are few and far between this time of year due to the winds .ill also get pics directly on the set up Link to comment Share on other sites More sharing options...
fin-addict Posted January 28, 2019 Report Share Posted January 28, 2019 Prop shaft or spun hub is what I would check first. Side to side movement on prop would have nothing to do with transducer placement. Splines on shaft and prop not fitting correctly. Could also be shaft to prop shaft cracked or bent. Jmo, has to be a shaft or prop problem. Seen it with early zouks back in the 90’s. Best of luck, fin Link to comment Share on other sites More sharing options...
HoneyB Posted January 28, 2019 Report Share Posted January 28, 2019 I can’t imagine why the dealer said a brand new prop would need to have a hub pressed in it to begin with.. something is fishy there Link to comment Share on other sites More sharing options...
dabear Posted January 28, 2019 Report Share Posted January 28, 2019 1 hour ago, fin-addict said: Prop shaft or spun hub is what I would check first. Side to side movement on prop would have nothing to do with transducer placement. Splines on shaft and prop not fitting correctly. Could also be shaft to prop shaft cracked or bent. Jmo, has to be a shaft or prop problem. Seen it with early zouks back in the 90’s. Best of luck, fin I am pretty sure that geeviam was trying to say a few things that could cause cavitation, I don’t think is was saying the transducer location could cause the prop hub to have play from side to side . I think he was saying that it is possible for a transducer location to disturb water flow to the prop and that disturbed water could cause a prop to have higher slip numbers. Fin-addict I agree with what you said about checking out that prop hub first . Link to comment Share on other sites More sharing options...
Guest DavidG Posted January 28, 2019 Report Share Posted January 28, 2019 Just left the dealer, they’ve moved the transducer out from under the transom and put it to the outside. Another test ride in a few hours. Tech advised that these new props that they put on now have a “ dampener “ effect and will have some movement. .??? I’ve included some pics and will advise how this test drive goes, just in case it helps someone elsebvi Link to comment Share on other sites More sharing options...
Guest DavidG Posted January 28, 2019 Report Share Posted January 28, 2019 Apologize for all duplicate pics, .........David Link to comment Share on other sites More sharing options...
geeviam Posted January 28, 2019 Report Share Posted January 28, 2019 That looks like a Talon SS prop, which has a SDS hub. Just tossing in a guess here, if it will help. The thru-hub exhaust on the Yamaha 4-strokes is hotter than the older 2-strokes, and there are cases of rubber hubs failing because they have overheated. How do I know? Because I cooked the rubber damper inserts in the SDS hub of my Talon SS prop when I installed a high performance trim tab plate on my VF115 lower unit, which was totally flat (no fin) and did not have the integrated water pickup, which scoops up and pushes more water through the hub to keep it cooled. The same overheating hub issue could occur if the motor was operated too high on the jack plate, or trimmed up too high, and the scoop on the trim tab plate didn't pickup enough water to cool the hub. The rubber SDS shift dampening inserts are inexpensive and easy to replace. Part # 6EK-45C82-09-00 at SIMYamaha.com. I can see how the prop could have some slop/play on the shaft if the rubber dampers were cooked and coming apart like mine did. Link to comment Share on other sites More sharing options...
geeviam Posted January 28, 2019 Report Share Posted January 28, 2019 Also, I don't think the location of your transducer is the cause of propeller cavitation. I thought it might be down near the keel, inside the transom pocket, before I saw your pictures. Link to comment Share on other sites More sharing options...
Guest DavidG Posted January 28, 2019 Report Share Posted January 28, 2019 That’s a nice to know information on this prop. Just prior to the last “ test drive” they had just replaced the rubber dampeners on the prop. The bracket has always been run in the lowest position and trim tabs have never been used. It’s only been in the water 5 times ( 2 of those with the salesperson and 1 with the tech) The boat has never felt “ right” from day 1. All my prior experience has been with deep-Vs so I thought it was a case of just getting used to it. After last test ride with the tech, We hadn’t gone a mile and he turned it around saying something is NOT right! Glad it wasn’t just me. I’m 58 and have learned more about prop cavitation and ventilation in the last week then I have my whole life!! Now that the transducer has been moved, we will be able to rule that out if the problem continues.Im thankful it’s winter in NE Fla before the Cobia start running along the beach. I’ll keep everyone informed and thanks to all for the useful information!....David Link to comment Share on other sites More sharing options...
Guest DavidG Posted January 28, 2019 Report Share Posted January 28, 2019 Geeviam,prior to today’s pics, the transducer was down in the transom pocket. I never knew it was that big as the dealer installed it. Now I need a sticker saying “ this is not a step” lol Link to comment Share on other sites More sharing options...
geeviam Posted January 28, 2019 Report Share Posted January 28, 2019 1 hour ago, DavidG said: Geeviam,prior to today’s pics, the transducer was down in the transom pocket. I never knew it was that big as the dealer installed it. Now I need a sticker saying “ this is not a step” lol I know what you mean - these new StructureScan and TotalScan transducers are huge! I think moving your transducer to where it is now was a good idea. Your jack plate looks like the heavy duty model for big block motors. What is the setback (size)? The reason I ask is because Atlas JPs add about 1.5" to 2" of height to the position of the motor on the transom. Redfisher transoms are already high without a JP. If your JP has a 4" setback, you may not be able to trim up your motor very much while running, without losing bite at the prop. A 6" setback (or more) is better for getting clean water to the prop. Hope this helps. Link to comment Share on other sites More sharing options...
Guest DavidG Posted January 28, 2019 Report Share Posted January 28, 2019 PROBLEM SOLVED!! Took the boat out with Tech an hour ago, after tech removed transducer out from under the transom cavity and placed it on transom ( pic enclosed) as well as replacing the prop dampener earlier. Current conditions: 55 degrees , water temp 62 , winds out of NE at 10-15, light chop in intracoastal. Boat had only CG required items, full tank of fuel, 2 men weighing approx 375 together. Boat ran and handled like never before. NO cavitation at all, no vibration. 47 mph @ 5400rpm not even wide open. Great grip through turns and no slippage. This tech will be having a discussion with the Tech that placed the transducer in the cavity. I want to Thank everyone for their suggestions as this helped as well as me learning a few things......David Link to comment Share on other sites More sharing options...
geeviam Posted January 28, 2019 Report Share Posted January 28, 2019 23 minutes ago, DavidG said: PROBLEM SOLVED!! Awesome!! Link to comment Share on other sites More sharing options...
fin-addict Posted January 28, 2019 Report Share Posted January 28, 2019 Color me wrong. Would not have thought it was the ducer but that is a biggie. Link to comment Share on other sites More sharing options...
Guest DavidG Posted January 28, 2019 Report Share Posted January 28, 2019 I don’t consider anyone wrong, all were valid things to look at. I did ask the Tech ( 25 years experience) whyYamaha changed to the rubber dampeners in their props and he advised it was mainly due to low and mid speeds where the prop would feel every piston causing more vibration at low/ mid speeds. He also advised about the heat issue as well with 4 stroke engines as Geeviam mentioned above. Thanks for all the help guys!.....David Link to comment Share on other sites More sharing options...
dabear Posted January 28, 2019 Report Share Posted January 28, 2019 DavidG I am so happy for you that your new boat cavitation problem has been corrected . Hope you get many many years of trouble free boating out of your new ride . 👍 Link to comment Share on other sites More sharing options...
Guest DavidG Posted January 28, 2019 Report Share Posted January 28, 2019 Geeviam, just measured and it has a 5 1/2 inch setback. I normally have run it all the way down and the only issue is you have to be careful when your bracket is all the way up not to scratch your cowling on the poling platform dabear , Thank you! I’ll still be paying for this thing from the grave lol. I told my wife to just bury me on it to save funeral expenses lol Link to comment Share on other sites More sharing options...
Guest DavidG Posted January 28, 2019 Report Share Posted January 28, 2019 I also need to give a Thank You to Atlantic Coast Marine here in Jacksonville! They will NOT let a customer leave unless their satisfied! Their techs are top notch!........David Link to comment Share on other sites More sharing options...
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