How to remove corroded screws...???

I just purchased a 1998 21 foot Crownline cuddy with trim tabs. Several (6 out of 8) of the screws on the starboard trim tab corroded to the point where the head broke off when I tried to remove them. Does anyone have any good ideas on how to remove these scres? I tried getting a pair of needle nose pliers on them but there isn't enough of the screws accessible. I am considering just glassing over these holes and drilling some new ones...Thanks in advance for the help!<br /><br />Don

Re: How to remove corroded screws...???

Depends on what the screws are made of. Since you say the heads twisted off, they're probably common steel or aluminum or brass (ss wouldn't twist off usually). If either of the former three metals, forget taking them out and it's unfortunate they were used in an underwater application to begin with. They're also corroded inside the glass (corrosion creeps). Don't try to drill them out, the drill bit will slip all over the place, making gouges. Sand flush and paint over, expecting some corrosion "leak" through the bottom paint each year. Live with it. But if you're going to re-attach the trim say a half inch to the left or right of the current screws, apply some Goop or other sealer under the attachment plate to isolate those screw shank tips from water.

Re: How to remove corroded screws...???

I've used a dremel tool with a cut off wheel to make a slot in broken screw.<br />It usually chews up the surrounding surfaces some though.

Re: How to remove corroded screws...???

If the screws are shot on one side, i would take them all out from both and start fresh(if your going to move one tab and reposition you should do both). Just out of curiosity what are the screws made of? If some idiot used plated screws to drill into the hull, or anywhere else on the boat in my opinion they need a slap!!! It is VERY important that you seal over the holes left when you change your srews... transoms are usualy wood core. It will soak in water and turn to goo over time. Good luck!<br /><br /> Jim

Re: How to remove corroded screws...???

If you could, use a dremel tool and carefully grind the screws a little below the surface of the fiberglass, say 1/8". Enlarge the area around the screw in a cone shape of about 1/2" diam, clean with acetone (then again) then fill with a marine epoxy intended for below waterline applications. Sand smooth when cured. Re-install trim tabs offset by 1/2" from original position using stainless screws and seal well using 3M 5200 or 4200 sealant. You will never know they were there.

Re: How to remove corroded screws...???

If you could, use a dremel tool and carefully grind the screws a little below the surface of the fiberglass, say 1/8". Enlarge the area around the screw in a cone shape of about 1/2" diam, clean with acetone (then again) then fill with a marine epoxy intended for below waterline applications. Sand smooth when cured. Re-install trim tabs offset by 1/2" from original position using stainless screws and seal well using 3M 5200 or 4200 sealant. You will never know they were there.

Re: How to remove corroded screws...???

Thanks for all of the responses. I do believe the screws are stainless steel since they seem to be non-magnetic. I am guessing the ones that corroded and broke off are original while the others may have been changed. I have no way of knowing though.<br /><br />Jilly, cuzner, RodC: You all suggest offsetting the tab by 1/2 inch or so and redrilling. I don't really want to have to do that - if I do I will have to move the other tab (no screws corroded) and I will have to move the upper cylinder attachments. Any comments on me sealing the holes where the screws broke with epoxy, reinstalling the tab in the same location but drilling 6 new holes about 1/2 inch from 'old' locations and inserting new screws? I obviously plan to change out all of the screws...<br /><br />Thanks for the comments! Don

Re: How to remove corroded screws...???

Originally posted by donskrin:<br /> .. Several (6 out of 8) of the screws on the starboard trim tab corroded to the point where the head broke off when I tried to remove them. ....Don

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Just curious as to whether you used a penetrating oil on these before you to tried to break them loose. If so, what kind and how long did you let it work? Asking 'cause I've heard there is a big variation in the effectiveness of different types; this seems like a real world 'test' report.

Re: How to remove corroded screws...???

http://www.northerntool.com/webapp/...00264674&cm_ven=TL&cm_pla=DF&cm_ite=powertool <br /><br />http://www.sears.com/sr/javasr/product.do?BV_SessionID=@@@@0085912198.1114716909@@@@&BV_EngineID=cchkaddehjhejmhcegecegjdghldgfi.0&vertical=SEARS&sid=I0033900150001800085&pid=00967 362000

Re: How to remove corroded screws...???

Hey Don..., if you stainless screws are corroding,there MAY be another issue to address. This may just be caused by bad grounding at a marina it was docked at before(especialy if it was salt water), but make sure your zincs are all in place and in good shape, and if your are not trailering consider instaling zincs on your tabs.Hope everything works out well!!<br /><br /><br /> Jim

Re: How to remove corroded screws...???

If the screws are stainless, They will be magnetic. Aluminum will not be magnetic. Try putting a piece of your stainless dinnerware next to a magnet and see what happens.<br />tabbott

Re: How to remove corroded screws...???

tabbott: stainless fasteners/screws are typically not magnetic. See the following link.<br /> http://www.manasquanfasteners.com/Stainless Steel Technical Data.htm <br />There are some "cheap" stainless fasteners on the market manufactured in Asian countries which are typically fine for anything except salt water immersion. I suspect that is what the previous owner used when he replaced a few of these fasteners.<br /><br />Lakelivin: I did not use a penetrant. The heads of the screws were barely being held on - 1 of them was actually missing when I pulled it out of the water. Some were totally gone - others look brand new which makes me believe some were inferior stainless.<br /><br />Poolecw: I will be heading to Northern tomorrow to try their extractor. If that doesn't work what do you think about my plan to epoxy the existing broken screw holes and drill out some new ones 1/2 inch away?<br /><br />cuzner: You certainly may be right. I have her on a trailer now and everything else looks fantastic. She only has 108 hours on her but I think she was kept in the water for part of her life anyway. I would absolutely put zincs on the tabs if I was going to leave her in the water.<br /><br />Thanks all for your replies. Does anyone have any comments about my plan to epoxy the broken screws and drill new holes??<br /><br />Thanks again. This is a great forum!

Re: How to remove corroded screws...???

center punch whats left of the screw and try a reverse drill bit ?

Re: How to remove corroded screws...???

Every once in a while I go nuts trying to read a post because it is displayed about twice the width of my computer screen. This is one of thoes posts. In order to read the post I have to pan across the screen making me dizzy. As is obvious by now that I'm not too computer savy. Is there something that I should be doing to keep the width on screen? Please help.<br />Thank you.

Re: How to remove corroded screws...???

Hey Lev, I was thinking the same thing, I gues us computer illiterates(sp) have to learn to scroll. Maybe JB can explain it.<br /><br /> Jim

Re: How to remove corroded screws...???

I think your idea of sealing up the old screws and re-drilling 6 new offset holes is a good idea. That way you can leave the tabs where they are as you pointed out. Just be sure to seal up everything really good. Now you will have 6 extra holes in the transom where water will be trying to get in.

Re: How to remove corroded screws...???

Good that you didn't use a penetrating oil!<br /><br />Using a penetrant in this case will swell the wood behind the fibreglass and make any screw even harder to get out.<br /><br />Cuzner's comment about dockside corrosion sounds valid. Some folks think that stainless doesn't corrode. It does, and especially where there are several different types of stainless in close proximity. Use 304 screws with a 316 tab, for instance, and the screws will corrode.<br /><br />The basic principle for fixing anything on a boat is to use higher quality fixings than the thing to be fixed.<br /><br />Check replacement screw quality before refixing your tabs.

Re: How to remove corroded screws...???

Originally posted by stillfishing:<br /> Good that you didn't use a penetrating oil!<br /><br />Using a penetrant in this case will swell the wood behind the fibreglass and make any screw even harder to get out.....

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Thats the kind of general knowledge I love to pick up in iboats!