Guest Posted January 21, 2013 Share Posted January 21, 2013 I recently upgraded the engine in my Marauder from a BUKH 10 to a Nani 21 and replaced pretty much everything except for the shaft strut. I have recently noticed a nasty vibration at pretty much any revs over 2000 (engine can go to 3600) I noticed the top of the strut support vibrating and was wondering if i need to beef it up to cope with the extra hp Here are some pics of the strut support structure. Was thinking either wood / glass supports each side or maybe 2 x stainless L brackets with a rigging screw on each so I can adjust the angle of the strut. Keen for any advise for the easiest way to resolve the issue as its in a really difficult place to work in Link to post Share on other sites
Marshy 30 Posted January 21, 2013 Share Posted January 21, 2013 Ive got a box load of Carbon here which ought to fix it!! Link to post Share on other sites
wheels 543 Posted January 21, 2013 Share Posted January 21, 2013 Are you absolutely positive the shaft is aligned perfectly. Link to post Share on other sites
Guest Posted January 21, 2013 Share Posted January 21, 2013 I was thinking that was the problem. It was aligned when the engine was installed and again when in the water. Might be best to get another alignment done first? Link to post Share on other sites
wheels 543 Posted January 21, 2013 Share Posted January 21, 2013 Maybe not. Just wanted to make sure we could tick that off the list. I assume you have stayed with the original shaft? Was there any chance the shaft now sits back further so as the Prop is further away from the strut?? Link to post Share on other sites
Guest Posted January 21, 2013 Share Posted January 21, 2013 I had a new shaft made. There is 1 inch clearance between strut and prop. I think I will check the allingnent first then beef up the strut somehow How much load is on that strut do you think? 1 inch shaft, 15 inch prop Link to post Share on other sites
wheels 543 Posted January 21, 2013 Share Posted January 21, 2013 It's a hard one to diagnose from a chair and monitor screen Two alignments to check remember. Out of centre and inline. How much that affects the vibration is down to what kind of coupling you have. Some can cope with more variation than others. But the aim is always to get as close as possible to perfect. As for strut, certainly building that up may help, even if just for it's own protection. Link to post Share on other sites
Guest Posted January 24, 2013 Share Posted January 24, 2013 Right. I have checked the alignment and its way out. I think the engine has settled into its mounts finally . Its so far out the I cannot align the engine to the shaft anymore. Plan is to take the boat out of the water, cut the old strut out and replace with a shiny new composite strut Will post some pics of the process once completed. Good old boats ay, nothing a little money cant fix... Link to post Share on other sites
Marshy 30 Posted January 24, 2013 Share Posted January 24, 2013 Nothing your money and someone else's time cant fix! Link to post Share on other sites
wheels 543 Posted January 24, 2013 Share Posted January 24, 2013 I think the engine has settled into its mounts finally . Its so far out the I cannot align the engine to the shaft anymore. I think something else must have been wrong when it was mated up. Mounts don't "settle". Don't worry about the strut. Sort the alignment by packing the mounts so as the engine sits where it is supposed to. Once that is sorted, you should be sweet and you shouldn't need to waste any money of a strut. Link to post Share on other sites
Guest Posted January 24, 2013 Share Posted January 24, 2013 It might not be the mounts. It may even be a bent strut...? The allingnent was mint when it went in the water Talked to another guy who had the same problem exept he snapped the strut clen off I will feel much better with a new strut I think The alignment issue is more port / starboard then up and down. I have ajustable mounts but there is only so much side to side I can go. Also, I think the stut was poked before I repowered. Link to post Share on other sites
rossd 16 Posted January 24, 2013 Share Posted January 24, 2013 I dont think your strut blade was mounted properly in the first place. I just have mine apart and looks the same sort of strut blade on the inside. I has a big bronze casting on the inside with 2 bolts through the blade and 4 through the hull. Yours doesnt seem to have anything holding it, wonder the water was'nt pissing in. Link to post Share on other sites
Guest Posted January 24, 2013 Share Posted January 24, 2013 Yea it looks dodgy az. Water is comming in slowly around the base only when motoring. No water comes in when stopped. I'm starting to think this was an accident waiting to happen... Link to post Share on other sites
Guest Posted February 11, 2013 Share Posted February 11, 2013 Over the last week I replaced the strut with a new carbon one Quite an easy job and not to expensive Link to post Share on other sites
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