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Old 30-07-2015, 17:37   #1
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How would you guys approach this fiberglass trim tab repair.

Got another question for you wonderful people. My boat came with this bit of damage on what used to be a trim tab on the keel. what happened was the yard crew hauled it out didn't realize that it was a non load bearing area and set the boat down on blocks on the area seen, it wasn't left there, as soon as they realized it wasn't load bearing the blocks were moved, so there's an approximately 4x6in square that has some crush damage (shown in first photo) on the bottom of the keel, there's also a crack in the trailing edge of the keel, again in what used to be the trim tab, also caused from the same incident.

how would you guys go about repairing these 2 cracks? my thought with the crack on the trailing edge is to fill it with epoxy with some high strength filler. as for the crush damage my thought it so grind away the damaged glass, use some foam as backing so I have a surface to lay up against and just layup several layers of glass over the damaged area, then fair it. and yes I know I need to bevel the good glass and lay up overlapping good glass. seem reasonable?

oh also. just to clarify, the area where this damage is located is on what used to be a trim tab that has had the hinge mechanism removed and the tab permanently fixed. I've attached a photo of the trim tab of another hinckley 38 in the yard just so we're all on the same page. my point is that where this damage is there's no chance for water to enter the hull, only the tab itself.

thanks very much guys, and sorry for the wall of text.

the damaged area on the trim tab (keel) bottom
IMG_0001 by Nathan Pablo, on Flickr

another view of the crush damage showing it's location on the hull
IMG_0003 by Nathan Pablo, on Flickr

the crack on the trailing edge of the trim tab (keel)
IMG_0004 by Nathan Pablo, on Flickr

and just for reference. this is what the trailing edge of these keels look like with the trim tab left as is. the area in question for me is all within the trim tab area.
IMG_0005 by Nathan Pablo, on Flickr
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Old 30-07-2015, 20:47   #2
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Re: How would you guys approach this fiberglass trim tab repair.

Use epoxy resin. Would wrap the crack in the back of the tab with a couple layers of matt/cloth. Why are you worrying about doing the repair?? Seems like the yard should handle it especially since they had another identical boat to figure out where to position the slings.
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Old 30-07-2015, 21:18   #3
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Re: How would you guys approach this fiberglass trim tab repair.

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Originally Posted by roverhi View Post
Use epoxy resin. Would wrap the crack in the back of the tab with a couple layers of matt/cloth. Why are you worrying about doing the repair?? Seems like the yard should handle it especially since they had another identical boat to figure out where to position the slings.
happened at a different yard than the one the boat is currently in. long story short the yard gave the previous owner the run around and was known for doing shoddy work as well so the didn't trust the yard to do the repair properly. previous owner is a 75 year old widow, just wasn't in a position to get into a drawn out fight over a minor repair with a bunch of backwater boatyard sleaze bags.
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Old 31-07-2015, 01:49   #4
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Re: How would you guys approach this fiberglass trim tab repair.

In response to your post #3. I don't think your plan sounds bad.

But when I looked at the geometry, my thought was that a naval architect might be able to re-design that, without the trim tab, and helping the water flow. [Apologies for spending your money.]

In a way, that trim tab is like a vestigial organ at this point. However, I think your idea to just bog it up and get on with life is practical.

Ann
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Old 31-07-2015, 05:54   #5
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Re: How would you guys approach this fiberglass trim tab repair.

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Originally Posted by Ann T. Cate View Post
In response to your post #3. I don't think your plan sounds bad.

But when I looked at the geometry, my thought was that a naval architect might be able to re-design that, without the trim tab, and helping the water flow. [Apologies for spending your money.]

In a way, that trim tab is like a vestigial organ at this point. However, I think your idea to just bog it up and get on with life is practical.

Ann
haha you're right but I'm less concerned about performance as this is a cruiser for me, not a racer.
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Old 31-07-2015, 18:36   #6
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Re: How would you guys approach this fiberglass trim tab repair.

Hello, My understanding of the trim tabs function is to add camber to the shape of the keel to make it more effective at generating lift, much the same as the flaps on an aircraft. At any rate, since the mechanism has been disabled so have any camber changing benefits. It could be that the boat will actually sail better with trim tab removed due to a reduction in the wetted surface, you may also find that the turning rate has increased to this same reduction in area so far aft. If the removal of the tab is easy, maybe try removing it and just fairing in the aft end of the keel to try it for a season. In the event that you didn't like the result and decided to repair the tab, it's removal would make the repair job far easier. Judging by the crack in your photo, I would say that the tab was built of two halves and bonded together. I personally would remove all of the damaged glass along with portions that have debonded to whatever the core is. Then cut 10:1 scarfs in the edges of the remaining glass and relaminate using vinyl ester resin and alternating layers of matt and cloth. Grind fair, add a barrier coat and you would be stronger than original across the seam where the crack formed.

Best of luck,

James

Quote:
Originally Posted by frozenhawaiian View Post
Got another question for you wonderful people. My boat came with this bit of damage on what used to be a trim tab on the keel. what happened was the yard crew hauled it out didn't realize that it was a non load bearing area and set the boat down on blocks on the area seen, it wasn't left there, as soon as they realized it wasn't load bearing the blocks were moved, so there's an approximately 4x6in square that has some crush damage (shown in first photo) on the bottom of the keel, there's also a crack in the trailing edge of the keel, again in what used to be the trim tab, also caused from the same incident.

how would you guys go about repairing these 2 cracks? my thought with the crack on the trailing edge is to fill it with epoxy with some high strength filler. as for the crush damage my thought it so grind away the damaged glass, use some foam as backing so I have a surface to lay up against and just layup several layers of glass over the damaged area, then fair it. and yes I know I need to bevel the good glass and lay up overlapping good glass. seem reasonable?

oh also. just to clarify, the area where this damage is located is on what used to be a trim tab that has had the hinge mechanism removed and the tab permanently fixed. I've attached a photo of the trim tab of another hinckley 38 in the yard just so we're all on the same page. my point is that where this damage is there's no chance for water to enter the hull, only the tab itself.

thanks very much guys, and sorry for the wall of text.

the damaged area on the trim tab (keel) bottom
IMG_0001 by Nathan Pablo, on Flickr

another view of the crush damage showing it's location on the hull
IMG_0003 by Nathan Pablo, on Flickr

the crack on the trailing edge of the trim tab (keel)
IMG_0004 by Nathan Pablo, on Flickr

and just for reference. this is what the trailing edge of these keels look like with the trim tab left as is. the area in question for me is all within the trim tab area.
IMG_0005 by Nathan Pablo, on Flickr
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Old 31-07-2015, 20:46   #7
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Re: How would you guys approach this fiberglass trim tab repair.

grind the trailing edge down and glass it in. if you just fill it it WILL crack again and it won't even need to be hit or touched by something. 2 to 3 days and that includes barrier coat. then bottom paint and splash. even less if you have all the tools and supplies on hand.
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Old 31-07-2015, 21:03   #8
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Re: How would you guys approach this fiberglass trim tab repair.

Quote:
Originally Posted by Lokiyawl View Post
Hello, My understanding of the trim tabs function is to add camber to the shape of the keel to make it more effective at generating lift, much the same as the flaps on an aircraft. At any rate, since the mechanism has been disabled so have any camber changing benefits. It could be that the boat will actually sail better with trim tab removed due to a reduction in the wetted surface, you may also find that the turning rate has increased to this same reduction in area so far aft. If the removal of the tab is easy, maybe try removing it and just fairing in the aft end of the keel to try it for a season. In the event that you didn't like the result and decided to repair the tab, it's removal would make the repair job far easier. Judging by the crack in your photo, I would say that the tab was built of two halves and bonded together. I personally would remove all of the damaged glass along with portions that have debonded to whatever the core is. Then cut 10:1 scarfs in the edges of the remaining glass and relaminate using vinyl ester resin and alternating layers of matt and cloth. Grind fair, add a barrier coat and you would be stronger than original across the seam where the crack formed.

Best of luck,

James
thanks for all the info James, greatly appreciated.
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