BROKEN CAVITATION PLATE

[Atropine]

First of all, thanks to everyone who helped me diagnose and fix the source of the water leak in my boat (hole in the y-pipe). Took it out yesterday and it works great. I also installed one of those "hydrofoil" cavitation plates to the existing Mercruiser cavitation plate to help it plane quicker. Well, when I got home, I noticed this crack in the factory cast cavitation plate...<br /><br />

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<br /><br />So, I need to get this fixed. First, I don't know if this can be welded because I think the existing housing is cast metal and I don't know how well that takes to being welded. Second, whatever stresses caused this crack need to be alleviated. I suppose I could just remove the hydrofoil, ut I would like to find some way to keep it. One idea I had was to get a 6" square piece of 1/4" aluminum plate and bolt it to the underside of the factory cavitation plate. There is enough clearance for the prop blades to do this. This would reinforce the cast factory cavitation plate, in essence "sandwiching" it between the aluminum and the hydrofoil plate. Any thoughts?

 

[TooTired]

Re: BROKEN CAVITATION PLATE

JB weld

 

[arboatdr]

Re: BROKEN CAVITATION PLATE

it can be welded with no problems, ground down and painted to look good as new. Should not cost too much to do. ( $50- 100) Looks like it's time for a new anode as well.

 

[outboardguy]

Re: BROKEN CAVITATION PLATE

Good to hear that you are in the water again.The Mercruiser drive is made of the same type of aluminum as their props,so you could try a local prop shop or welder.Take a look at this previous post<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=29;t=011007 <br /><br />Good Luck

 

[Bondo]

Re: BROKEN CAVITATION PLATE

That's Why I like Trim Tabs, instead of those Whaletails......<br />As Sated, the Housings are cast Aluminum.... Any Welding Shop can fix it.......

 

[Atropine]

Re: BROKEN CAVITATION PLATE

Someone mentioned something about an ANODE; is this the thing that looks like a pumice stone in the pic? If so, I have more than one of them on my stern drive. What is the purpose; to electrically inhibit buildup up mineral deposits on the stern drive? Would I damage anything by covering up the underside of this anode with an aluminum plate?

 

[flashback]

Re: BROKEN CAVITATION PLATE

yes the anode is a sacrifical piece of zinc, it is less noble than the aluminum and will draw stray electrolisis to it instead of the outdrive casting......by all means replace it and make sure the metal under it is clean and free of paint. (in other words, a good connection)

 

[Bondo]

Re: BROKEN CAVITATION PLATE

" to electrically inhibit buildup up mineral deposits on the stern drive? "

NO, Nothing to do with mineral deposits.......<br />It Slows the Lost of Metal from your drive....<br /><br />

"Would I damage anything by covering up the underside of this anode with an aluminum plate?"

YES, Don't Cover, or Paint the Anodes..... They Won't be able to do their Job if Covered in Any Way............

 

[MrBill]

Re: BROKEN CAVITATION PLATE

Had the same problem that you have as a result of the fin mounted to the outdrive. Certain fins force you to mount very close to the rear edge of the plate...and pressure, or weight applied to it causes it to break. Sometimes they get caught on the ladder. I used JB Weld with great success...apply liberally, grind off and paint. Two years now, no problems, but didn't put the fin back on. If necessary, the broken piece can be heat welded.<br /><br />If I get the urge to use a fin again, I'd go with the two piece Doel Fin that can mount further forward on a meatier portion of the plate.<br /><br />Don't let people use the fin as a step to get in the boat and you'll save a lot of hassle next time.

 

[jbh350]

Re: BROKEN CAVITATION PLATE

The best all-a-round fix, is to take it to a prop shop and have it welded. Then take off that fin and sell it at your spring garage sale. Then go down an pick yourself up a set of Bennett trim tabs, you will love them.