rockfisherman Posted March 6, 2012 Share Posted March 6, 2012 (edited) Hi raiders About a year ago I purchased a brand new 4m tinny, trailer and a 15hp outboard. For while now I've been wondering why it becomes uncontrollable once it picks up speed. Now although I read the manual, I somehow missed the part where it states the cavitation plate must be between 0-25mm below the lowest point of the hull. This is what I've got More than 60mm, is this what it is or am I incorrect? The out board can't be taken up any further. What are my rights in this situation ? This guy has gone and sold me something that Dosnt comply with manufacturers specifications. I just want to get my facts straight before I confront this guy. Edited March 6, 2012 by fishingphase Link to comment Share on other sites More sharing options...
Geoff Posted March 6, 2012 Share Posted March 6, 2012 Hi raiders About a year ago I purchased a brand new 4m tinny, trailer and a 15hp outboard. For while now I've been wondering why it becomes uncontrollable once it picks up speed. Now although I read the manual, I somehow missed the part where it states the cavitation plate must be between 0-25mm below the lowest point of the hull. This is what I've got More than 60mm, is this what it is or am I incorrect? The out board can't be taken up any further. What are my rights in this situation ? This guy has gone and sold me something that Dosnt comply with manufacturers specifications. I just want to get my facts straight before I confront this guy. The motor is too low & most likely the cause of your problem but I think , after a year , is a bit long to take it back for some sort of claim . Why can't the motor be raised ? Can you add some pic's of the motor mount from both outside & inside. Geoff Link to comment Share on other sites More sharing options...
rockfisherman Posted March 6, 2012 Author Share Posted March 6, 2012 I'm sure consumer affairs would have something to say. I'll get some pics up when I get home. Cheers Link to comment Share on other sites More sharing options...
Marlin01 Posted March 7, 2012 Share Posted March 7, 2012 Geoff, The cav plate being too low will not cause the problems you have, in fact just the opposite it will improve turning control due to increased effective "rudder" area. The fact it is sitting lower than required may be slowing you down a little but will be assisting in preventing prop cavitation. Other options are to increase the tiller friction damping the effects of prop tourque which will feel as if the tiller is being pulled to one side whilst accelerating. Talk to your supplier about your problem and ask him for suggestions or solutions before getting him offside. Good luck Cheers Marlin01 Link to comment Share on other sites More sharing options...
rockfisherman Posted March 7, 2012 Author Share Posted March 7, 2012 Geoff, The cav plate being too low will not cause the problems you have, in fact just the opposite it will improve turning control due to increased effective "rudder" area. The fact it is sitting lower than required may be slowing you down a little but will be assisting in preventing prop cavitation. Other options are to increase the tiller friction damping the effects of prop tourque which will feel as if the tiller is being pulled to one side whilst accelerating. Talk to your supplier about your problem and ask him for suggestions or solutions before getting him offside. Good luck Cheers Marlin01 marlin01 The tiller does feel as though it's being pulled to left and requires a bit of strength to hold while its running...and it is fairly centered, I was going to counter it by nudging the outboard to the left a bit. Would that make a difference? Fishingphase Link to comment Share on other sites More sharing options...
Juggs Posted March 7, 2012 Share Posted March 7, 2012 (edited) All the brands have differing opeinions on true shaft length can be up to 50mm between them all. then you add in manufactures also being slightly different and bingo you have the problem you have now The engine does not have to sit flush on the transom on my last tinny it was raised 50mm, shows us a photo of the top of the transom and where the engine clamps are sitting When you say uncontrolable, i assume you mean at speed it wants to pull in one direction or the other this is easily fixed by adjusting the fin in front of the propeller on the bottom of the cav plate. Adjust it in small increments in the oposite direction it is pulling it will only need a few mm adjustment each time till you get it right edit i just noticed yours does not have this feature, what engine and hp is it? and back on the topic of cav plate height, as water runs under a alloy hull and comes out the back it is actually higher then the bottom of the hull. the boat does not sit on top of the water so many cav plates need to be 10-20mm above the bottom sheet of the hull, nearly every tiller boat i have had this has been the case Edited March 7, 2012 by Juggs Link to comment Share on other sites More sharing options...
rockfisherman Posted March 7, 2012 Author Share Posted March 7, 2012 (edited) All the brands have differing opeinions on true shaft length can be up to 50mm between them all. then you add in manufactures also being slightly different and bingo you have the problem you have now The engine does not have to sit flush on the transom on my last tinny it was raised 50mm, shows us a photo of the top of the transom and where the engine clamps are sitting When you say uncontrolable, i assume you mean at speed it wants to pull in one direction or the other this is easily fixed by adjusting the fin in front of the propeller on the bottom of the cav plate. Adjust it in small increments in the oposite direction it is pulling it will only need a few mm adjustment each time till you get it right edit i just noticed yours does not have this feature, what engine and hp is it? and back on the topic of cav plate height, as water runs under a alloy hull and comes out the back it is actually higher then the bottom of the hull. the boat does not sit on top of the water so many cav plates need to be 10-20mm above the bottom sheet of the hull, nearly every tiller boat i have had this has been the case Ok so the cavitation plate should really be more or less in line with the bottom of the hull, and adjust the fin in front of the proppelor Edited March 7, 2012 by fishingphase Link to comment Share on other sites More sharing options...
Juggs Posted March 7, 2012 Share Posted March 7, 2012 Ok so the cavitation plate should really be more or less in line with the bottom of the hull, and adjust the fin in front of the proppelor basically yes you can use apiece of timber on top of the transom to get height and bolt the engine in place, 2 boats i had the clamps did not bite into anything it did have four bolts holding it on though though i can not see a trim tab on your engine Link to comment Share on other sites More sharing options...
dunc333 Posted March 7, 2012 Share Posted March 7, 2012 (edited) i would lift motor up 80mm and see how you go and once you get motor height correct you can play with your prop size (pitch),also measure and check that your motor is in dead center of transom ,let us know what you do as very interesting,was it a boat ,motor ,trailer package you purchased?? also what length leg have you got on that motor,just by looking but not sure 100% it might be the 20inch shaft (leg) they do make a 15inch which would be better for your hull ,if im right you could have some comeback with dealer if you have the longer shaft when you purchased boat ?? cheers dunc333 Edited March 7, 2012 by dunc333 Link to comment Share on other sites More sharing options...
rockfisherman Posted March 7, 2012 Author Share Posted March 7, 2012 Yes it was a boat, motor, trailer package. I can't find an adjustable fin in front of the propellor. Link to comment Share on other sites More sharing options...
Geoff Posted March 7, 2012 Share Posted March 7, 2012 I can't find an adjustable fin in front of the propellor. The trim tab is fitted at the end of the cav plate. It's possible that 15hp motors are not supplied with a trim tab. As to the height , I can see your problem regarding the adjustment. Review the options mentioned by others but I suspect , that at the end of the day , you will need to have an aluminium box section welded on to the top of the transom so the motor can be lifted & you have something to clamp onto. PM Gary at Serious Stainless , he may have material in stock Geoff Link to comment Share on other sites More sharing options...
Juggs Posted March 7, 2012 Share Posted March 7, 2012 put up a picture with the engine tilted showing us where the engine mound bolt holes are 4 bolts and no clamps is more then adequate to hold it on Link to comment Share on other sites More sharing options...
rockfisherman Posted March 7, 2012 Author Share Posted March 7, 2012 (edited) Well here lies another problem,if I raise it the desired height only 2 bolt holes will fix into some thing Edited March 7, 2012 by fishingphase Link to comment Share on other sites More sharing options...
BFB Posted March 7, 2012 Share Posted March 7, 2012 Part of the problem could be the trim of the motor. I know that if my motor is not trimmed correct the steering pulls like hell at full speed but trim it correct and it drives like a dream. Try to trim the motor out a bit and see how that goes. Link to comment Share on other sites More sharing options...
rockfisherman Posted March 7, 2012 Author Share Posted March 7, 2012 Part of the problem could be the trim of the motor. I know that if my motor is not trimmed correct the steering pulls like hell at full speed but trim it correct and it drives like a dream. Try to trim the motor out a bit and see how that goes. ok I'll need to have a look at that as well Link to comment Share on other sites More sharing options...
Juggs Posted March 7, 2012 Share Posted March 7, 2012 id say as someone else said a piece will have t be welded in and braced to get more height can you measure from the top of the transom to the bottom sheet of the boat ? Link to comment Share on other sites More sharing options...
dunc333 Posted March 7, 2012 Share Posted March 7, 2012 its the wrong size motor fitted from dealer ,maybe huey might pitch in,to me its a dealer problem created by the dealer. Link to comment Share on other sites More sharing options...
a boat Posted March 7, 2012 Share Posted March 7, 2012 Hi, +1 to what Dunc said it "looks" like from the pitcures you have posted you have a long shaft engine on a shjort shaft boat. Take a photo when you are standing back so we can see the whole engine and transom-not close ups, or better yet swing by with it one day and we can have a look in person. Cheers, Huey. Link to comment Share on other sites More sharing options...
ray henry Posted March 7, 2012 Share Posted March 7, 2012 its the wrong size motor fitted from dealer ,maybe huey might pitch in,to me its a dealer problem created by the dealer. Link to comment Share on other sites More sharing options...
rockfisherman Posted March 7, 2012 Author Share Posted March 7, 2012 I'm going to call the dealer this morning Hi, +1 to what Dunc said it "looks" like from the pitcures you have posted you have a long shaft engine on a shjort shaft boat. Take a photo when you are standing back so we can see the whole engine and transom-not close ups, or better yet swing by with it one day and we can have a look in person. Cheers, Huey. thanks Huey, always the gentlemen you are. I just spoke to him and he insists that's the way it supposed to be. I asked him what the size difference is between the long shaft and the short shaft is, he said 50mm, I said then that would be perfect, he said no. I just sent him an email saying I'm going to get more second opinions. If I have enough people tell me that he sold me something that wasn't configured correctly I'm going to ring fair trading, and I hope he's smart enough to realize that's what's coming if Dosnt get off his rear end and do something about it real soon. Link to comment Share on other sites More sharing options...
a boat Posted March 7, 2012 Share Posted March 7, 2012 Hi, the difference between short shaft and long shaft is 5 inches, so not sure who this guy is but that is worry if he thinks it is 50mm or 2 inches. Short shaft transoms are 15 inches and longshaft are 20 inches so measure your transom to see what your hull is. Cheers, Huey. Link to comment Share on other sites More sharing options...
Juggs Posted March 7, 2012 Share Posted March 7, 2012 Hi, the difference between short shaft and long shaft is 5 inches, so not sure who this guy is but that is worry if he thinks it is 50mm or 2 inches. Short shaft transoms are 15 inches and longshaft are 20 inches so measure your transom to see what your hull is. Cheers, Huey. what brand of outboard is it im asuming merc or tohatsu from the black paint all outboat brands have a different measurement for long and short shaft, one of my merc 25hps measured 22.5 inches from inside the engine mount to the cav plate Link to comment Share on other sites More sharing options...
rockfisherman Posted March 7, 2012 Author Share Posted March 7, 2012 It's sail outboard motor 15hp, one of the many brands coming out of china right now. Hi, the difference between short shaft and long shaft is 5 inches, so not sure who this guy is but that is worry if he thinks it is 50mm or 2 inches. Short shaft transoms are 15 inches and longshaft are 20 inches so measure your transom to see what your hull is. Cheers, Huey. Ok so we've established he's given me the wrong type of motor. I just got off the phone with him and he's telling me I need to adjust the angle of the trim.Also, that they tried putting on a short shaft but it didn't fit. He didn't sound to keen on sorting my problem. Link to comment Share on other sites More sharing options...
a boat Posted March 8, 2012 Share Posted March 8, 2012 Ok so we've established he's given me the wrong type of motor. I just got off the phone with him and he's telling me I need to adjust the angle of the trim.Also, that they tried putting on a short shaft but it didn't fit. He didn't sound to keen on sorting my problem. Hi, that is not what we mean, the transom height is from the keel to the top of the transom-not the width of the area where the outboard goes. For years the industry STD has been 15 or 20 inches. As I said take a photo standing back from the boat showing the complet outboard and transom. Cheers, Huey. Link to comment Share on other sites More sharing options...
dunc333 Posted March 8, 2012 Share Posted March 8, 2012 (edited) 99% sure you have the sail 15hp 2stroke with the 20inch shaft that he must of had in stock and he didnt have any 15inch in stock at the time of your purchase so he fitted the 20inch instead,just my opinion,also is your boat a baystar 4.metre if so your transom height would be 500mm Edited March 8, 2012 by dunc333 Link to comment Share on other sites More sharing options...
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