Scarfing a strake for repair..

240sxguy · Post by **240sxguy** » Thu Nov 04, 2010 10:15 am

I need to scarf in a piece to fix the last 3-4" of one of the strakes of my boat. The PO punched a hole in it somehow and screwed a backing block to it and packed it full of stuff. I cleaned out the hole and am curious, is there any way at all to replace just the end without removing it from the boat? Ill remove it if I have to, but that is a crapload of expensive hardware to replace!

No, John, I am not going to take the entire boat apart! lol

Thanks!

Evan

txcaptdan · Post by **txcaptdan** » Thu Nov 04, 2010 2:21 pm

Yes, you can replace a partial lap at the end. I replaced several at the transom on the starboard of my Cruisers Inc. Here is a link to a repair I made on the side of the same boat, http://thompsondockside.com/views/viewtopic.php?t=2840

I would go back far enough from the transom so that you will contact at least several ribs with new lap. I ground the scarf back 4" and made the lap over a rib. You will want to carefully remove bolts top and bottom so that you can reuse them when attaching old laps to new lap, each rib has a screw into it through lap. Save lap taken out so that you can replicate it, pay close attention to how edges of removed lap is shaped to fit into older laps and to the actual thickness of the lap, we had to plane them to get them to size. I sealed mine with 5200 when I reassembled them. I have some detail images of that repair if you need them.

Disassemble carefully and use new hardware if you can.

240sxguy · Post by **240sxguy** » Thu Nov 04, 2010 3:41 pm

Dan, looks great! I have a fein multimaster I can likely use to scarf in the piece too. I can handle this!

Evan

larryejoh · Post by **larryejoh** » Sat Nov 06, 2010 8:55 pm

Dan

What did you use to grind the scarf joint on the strake. I need to replace about a foot on a couple of mine at the transom. I didn't want to remove the entire strake to do this.

Larry

240sxguy · Post by **240sxguy** » Sun Nov 07, 2010 6:21 am

Larry, my first thought would be either an angle grinder or belt sander if you could get it in there.

larryejoh · Post by **larryejoh** » Sun Nov 07, 2010 12:09 pm

I'm not sure how to cut under the lap of the next outboard plank without damaging it? Larry

john · Post by **john** » Sun Nov 07, 2010 5:45 pm

For ginding I would use a 10,000rpm 4" grinder with 30 grit paper, I would use a utility knife to carve any remaining material. Maybe a dremel tool!

For a hole I see nothing wrong with a circular tapered plug expoxed inplace!

All this went thru my mind as my engine was trying to fly up in my Cruisers several weeks ago, after hitting a tree stump!

My boat is put together with 5200! Great till you .need to take it apart, then it's carve and grind it apart.

Believe I would make new pieces at least 18" long

txcaptdan · Post by **txcaptdan** » Mon Nov 08, 2010 5:41 pm

I used a belt sander to create scarf then chiseled and hand worked area under lap above. A multimaster tool seems to be a good choice for that area also. I reused holes from hardware to reattach new lap. Had to adjust thickness of standard marine plywood to match old dimensions.

Dry fit and trim until it fits perfect.

larryejoh · Post by **larryejoh** » Mon Nov 22, 2010 7:28 pm

What type of glue or epoxy did you use on the scarf joint?

240sxguy · Post by **240sxguy** » Tue Nov 23, 2010 6:18 am

West systems is my conclusion after much reading on woodenboat forums.

John Hart · Post by **John Hart** » Tue Nov 23, 2010 3:49 pm

For Epoxy, I suggest Smith's... Laminating and Layup Epoxy.. I believe they are cellulose based, and probably less brittle than other epoxies.

PeterZ · Post by **PeterZ** » Wed Nov 24, 2010 5:00 pm

Hi Guys, Nice Thread, hope some are still reading!!

Evan, I thought you were going to sell your boat!!!! Guess not, glad to hear!!;->

I have a scarf question. I was reading in some Wooden Boat forum about preparing a scarf that has some ratio of length to depth (can't recall the ratio right now). Then I saw an add for some jig your could buy for a power planer to make pristine scarfs. So I naturally assumed this is what you do, of course having to remove the strake(s) first. Well I guess not, ... do you all out there make these scarfs with belt sanders and other tools and do it by eye? If it works, it works. Seems to me you would have an issue with having a ‘rounded’ scarf on the surface due to nature of belt sanding and the joint would not be tight across the entire joint.

I was reading Danenberg's volume 2 book and he seems to cut bad portions of the strakes out square and has a procedure of measuring and fitting in a new piece using butt blocks behind the joint of the old and new piece of the strake. I don’t think I would what to see butt blocks everywhere on the inside, … perhaps these are hidden in boats he is working on. He makes one comment about scarfing them in but says you need to take the strake completely off?? So what’s the consensus here?? How have you guys out there done it?

BTW, I see in Dan's thread that he used some kind of marine bondo to feather out the new strake piece. Won't this eventually crack from vibration in the hull? Wondering how brittle this stuff is. Danenberg does not mention how he covers up the 'cracks' between the new and old work on the outside, seems to me it would be evident in the finished paint job. Whats typically done here to cover these seams?

Thanks

Some day I will have a boat to work on, ... for now its fun to live through you guys, its cheaper that way ;->, however no reward ;-<

Regards
Peter

240sxguy · Post by **240sxguy** » Wed Nov 24, 2010 5:49 pm

Peter, yeah, I am going to keep trucking on this one.

As to your other questions, I dunno. If your really dying for a project come pick my boat up. Let me know when it's finished and Ill come get it!

Evan