{"id":1253,"date":"1999-11-30T00:00:00","date_gmt":"1999-11-30T05:00:00","guid":{"rendered":"https:\/\/setsail.com\/?p=1253"},"modified":"2015-10-16T12:06:27","modified_gmt":"2015-10-16T17:06:27","slug":"opposite-rotation","status":"publish","type":"post","link":"https:\/\/setsail.com\/opposite-rotation\/","title":{"rendered":"Opposite Rotation"},"content":{"rendered":"
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What effect is there on propeller performance and vibration when fitted in the opposite rotation to that recommended by the boat builder?<\/p>\n

I just purchased a 9 year old Grand Soleil Maxi One (19.5m) and am having a lot of problems with engine & MaxProp giving a lot of very bad vibrations and engine not being able to obtain correct cruising revs (should be about 2700\/2800 rpm–and getting black smoke when revving above 2200rpm).<\/p>\n

Obvious answer is the prop is over pitched. However, on checking with MaxProp rep here in Athens, he just serviced and refitted the prop with 20 degs with right rotation. According to the Manual on board from the builders (Canteir del Pardo) the prop should be 14 degs–Left Rotation.<\/p>\n

Of course the over pitching of the prop answers the problem of the engine not revving etc, but would the wrong rotation cause increasingly bad vibrations the more rpm’s applied?<\/p>\n

I need some urgent advice because the incorrect running of the engine over the last 8\/9 years (by previous owner) has caused all sorts of problems including overheating, broken pipe in heat exchanger and blown gasket leading to water into the cylinders and turbo etc on my recent outing with service engineers on board testing the engine after service. Thus, decided to put new engine as do not want to have further trouble\/time\/expense of trying to renew\/overhaul existing engine.<\/p>\n

Obviously have to find also a solution for the bad vibrations, but I cannot get Maxprop or del Pardo to reply to my emails and faxes. <\/p>\n<\/div>\n

<\/p>\n

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Hi George: <\/p>\n

I’ll try to help. <\/p>\n

1-Max Props work the same in both directions since they do not have any airfoil shape. <\/p>\n

2-Some transmissions can be used in both directions as well, sometimes with a very slight difference in reduction gear. When this is the case, you chose the rotation direction so that you get stern walk in the best direction for how you normally dock (or dock most often). <\/p>\n

3-Assuming your transmission can be used ahead in both directions, you then can consider which way to pitch the prop. If you allow the engine to develop full rpms, with high speed engines and Max props you typically have some face cavitation–which makes the prop less effective. However, if you over-prop, you have to be very careful not to overload the engine. There is a chapter on this subject in our Offshore Cruising Encyclopedia.<\/p>\n

4-The vibration could be coming from a bent prop shaft–it only takes a tiny bend to vibrate like crazy. It could be coming from an alignment problem. Or the prop itself could be out of balance. You can check for a bent shaft out of the water by rotating the shaft and sighting carefully for a big bend. Small bends need to be checked in a machine shop.<\/p>\n

5-I would do the following in this order:<\/p>\n

A-Verify the transmission can be run in both directions. If not, correct the direction of rotation for the prop (and change your shift cables accordingly!). B-Check prop shaft flange to transmission alignment. C-Make sure the prop is clean. D-Verify the prop is balanced and the prop shaft is not bent.<\/p>\n

Good Luck–Steve <\/p>\n

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What effect is there on propeller performance and vibration when fitted in the opposite rotation to that recommended by the …Read More<\/a><\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10,15],"tags":[],"class_list":["post-1253","post","type-post","status-publish","format-standard","hentry","category-tech-talk","category-yacht-propellor-faqs"],"_links":{"self":[{"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/posts\/1253"}],"collection":[{"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/comments?post=1253"}],"version-history":[{"count":1,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/posts\/1253\/revisions"}],"predecessor-version":[{"id":36015,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/posts\/1253\/revisions\/36015"}],"wp:attachment":[{"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/media?parent=1253"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/categories?post=1253"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/setsail.com\/wp-json\/wp\/v2\/tags?post=1253"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}