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Prow prang predicament: practical patching protocol, please.

Jul 30, 2019
208
Seaward 25 777 Fort St. James
I admire all of you who can dock without a motor. Actually, I admire the rest of you who can dock with a motor! It seems that I can do neither. At the end of last season, on a glass calm day, as I carefully inched my way back up to the vicious, unprotected and rusty steel edges of what passes for a dock at Alberta Beach, on Lac Ste. Anne in Alberta, my ancient Johnson died as I swapped into reverse. We were only carrying about a knot, but that was enough to attract the attention of old Isaac Newton, who abruptly woke up from slumbering through the past several decades since I last saw a physics book, raised an admonitory finger and shouted: "E=mv2, dumbass!" This was followed by a crunch, immediate cessation of forward motion, and one of those reproachful looks from my wife. You know the sort, I feel sure....

The damage is not great. Here are pictures.
booboo 01.JPG

booboo 02.JPG


I have searched the forum on the topic of repair, and have seen Marine-Tex recommended. I do not have any of that, yet anyway, but do have automotive Bondo on the shelf. I am wondering if Bondo would work, or should I buy a marine filler like the Marine-Tex?

Also, how much sanding back or chipping away should I do on the damaged area? It is well above the waterline.

Thanks in advance for your thoughts.

Bob
 
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Likes: Phil Herring
Oct 22, 2014
16,081
CAL 35 Cruiser moored EVERETT WA
Bob, I would "grind" it back till I found solid material. No loose, crushed chunks. Does not look like it will be much. Then I'd get some thickened epoxy and some cloth and start filling in the hole. Once I had a solid surface again and mostly shaped as before, I would grind it back to shape. Once recovered the proper shape I would get some epoxy filler and fill/shape the bow removing the imperfections from the surface. Sand to finished shape and then paint as before. It will possibly be stronger than original, the epoxy will adhere to the boat material and is less likely to suck up water.

I do not like "bondo" for this repair.

Check out the folks at Jamestown Distributors. Jamestown Distributors

They carry the type of product that will serve your needs, and they have a lot of DIY instruction to help you use the products.
 
Oct 19, 2017
6,936
O'Day 19 Littleton, NH
:plus: What js typed.
It is my understanding that Bondo is harder than the surrounding gelcoat. This means, when you try to sand your repair patch smooth and flush, the gelcoat will sand away before the Bondo does. Hard to get a good shape that way. It also absorbs water and doesn't stick as well.

To fill your gouge, chop up the glass and mix it into the epoxy, that way you won't get folds and wrinkles in the cloth that could create air bubbles. Then cover the sanded area with woven glass cloth for strength.

-Will (Dragonfly)
 
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Likes: jssailem
Oct 22, 2014
16,081
CAL 35 Cruiser moored EVERETT WA
Oh.. What @Will Gilmore said reminds me. Use cloth and cut it up. Do not use "chopped Mat" with epoxy. The chopped mat you buy has a binder on it. It is designed for Polyester Resin not epoxy.

You can take a piece of fiberglass cloth and cut it up to enhance the strength of the repair. Or you can cut small pieces of cloth to fit inside the hole, wet them down and layer them. Just be sure to compress the layers and get the bubbles out of the mix. Check out the "BoatToday" YouTube videos. Andy is a great teacher of boat repair.
 
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Likes: Will Gilmore
May 17, 2004
3,469
Beneteau Oceanis 37 LE Havre de Grace
Check out the "BoatToday" YouTube videos. Andy is a great teacher of boat repair.
:plus: for Andy, but the channel name is BoatworksToday. I don’t know if glass would be necessary. Just thickened epoxy and/or something like the Total Boat fairing compound might be good enough, though I suppose adding some glass would be stronger.

Also, on the glass calm days, try to carry well less than a knot when that close to your dock. It’ll give you more time to adjust and more margin for error, while probably still leaving you plenty of steerage.
 
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Likes: Noodat Lady
Jul 30, 2019
208
Seaward 25 777 Fort St. James
Thanks for the detailed recommendations, js and Will. Some excellent tips. I've got everything except the epoxy, so will proceed along those lines once I've bought some. Great idea on the cut cloth.

Bob
 
Jan 11, 2014
7,824
Sabre 362 113 Fair Haven, NY
Epoxy adheres better than polyester and does not shrink. Polyester, which Bondo uses does not adhere as well and does shrink over time.

Check the West System website for advice, they have a manual you can download, read online or purchase. Westsystem.com
 
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Likes: jssailem
Jan 11, 2014
7,824
Sabre 362 113 Fair Haven, NY
We were only carrying about a knot, but that was enough to attract the attention of old Isaac Newton, who abruptly woke up from slumbering through the past several decades since I last saw a physics book, raised an admonitory finger and shouted: "E=mv2, dumbass!"
Never approach a dock at a speed faster than you want to hit the dock.

@capta has an appropriate tag line. Look for one of his posts. :biggrin:
 
Jul 30, 2019
208
Seaward 25 777 Fort St. James
To defend myself just a wee bit: the dock was built by B.L.Zebub & Sons to a design initially used by the Wehrmacht in constructing defences on the Normandy coast against an Allied beach landing. It's as bad a dock as you could find. More just a breakwater built out of heavy steel sections smacked into the lakebed then hacked off kind of even using a torch. Not a good picture, but here we are:
20200111_123002.jpg

You might note that there is no-thing, nae sae much as a wee bollard, to put a line around.....

I would say that the way we carried would have been just fine on any normal dock with even timber edging, let alone the rubber or plastic dock buffers that many of you would be accustomed to. We have 4 fenders out, but they play Russian roulette with the \/ \/ \/ section of the dock edge, and of course are useless at the prow. Long term the solution is to avoid that boat launch, which we shall from now on. I shall also work on my docking skills, or lack thereof.

Bob
 
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PaulK

.
Dec 1, 2009
782
Sabre 402 Southport, CT
Another anti-bondo aficionado here. It absorbs water (Look up hydroscopic.). After it does that all season, what happens to it in a January freeze? It pops off as the expanding ice blows it apart!!

As others suggest, epoxy is the way to go. It looks small enough that one MarineTex box would be sufficient. That would avoid having to spend more on larger kits of epoxy and filler than you need.

Correction: hygroscopic, as Bob suggests below.
 
Last edited:
Jul 30, 2019
208
Seaward 25 777 Fort St. James
Isn't that hygroscopic with a g? Hydroscopic is involved with the science of hydroscopy, basically viewing things underwater. As an ex-oil rig diver and subsequently marine biologist I did a lot of hydroscopy without absorbing an inordinate quantity of water. Bondo must indeed be covered in an impermeable layer in automotive applications. But, don't worry, no Bondo for the O'Day.

Thanks for the tip on Marine-Tex. A penny saved is a penny more for the tax man.

Bob


Another anti-bondi aficionado here. It absorbs water (Look up hydroscopic.). After it does that all season, what happens to it in a January freeze? It pops off as the expanding ice blows it apart!!
 
Last edited:
Jul 30, 2019
208
Seaward 25 777 Fort St. James
That’s not really that deep. I might just gelcoat and paint
I like John's "grind back to solid stuff" idea in the first reply. The damaged area probably never got really wet after this happened, but it does look as if some delamination occurred. I am open to all suggestions. Well, maybe not quite all .....

Bob
 
Oct 22, 2014
16,081
CAL 35 Cruiser moored EVERETT WA
Bob would love the see the “after I Fixed it” pictures.

Your not the first nor the last boat owner to use the Prow to stop the boats forward progress. Maybe your post will pay it forward to the next skipper with a ”Prow prang predicament”. :biggrin:
 
Jul 30, 2019
208
Seaward 25 777 Fort St. James
Thanks John and everyone. "After" pictures promised. Should have time to get started on it next week, especially as we have a whole week with daytime temperatures forecast to go no higher than -21F, -32C. Don't ask me about the lows..... Luckily I got the furnace in our warehouse building fixed this week!

A few other small jobs to do on the boat at the same time, like two new cam cleats, and maybe a jib downhaul.

Bob
 
Nov 3, 2018
68
Cape Dory, Albin 300ms Motorsailer, Vega Baltimore
:plus: For the boat works today (BWT) videos. I’d be inclined to grind it back to good glass, lay in a couple of layers using either epoxy or polyester, sand smooth and then apply Gel coat If the boat hasn’t been painted. Otherwise paint. Andy at BWT can walk you through it. BTW Love your writing! Next time the Admiral scowls at me for docking by brail I’ll just say it was a PPP!
 
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Jul 30, 2019
208
Seaward 25 777 Fort St. James
:plus: For the boat works today (BWT) videos. I’d be inclined to grind it back to good glass, lay in a couple of layers using either epoxy or polyester, sand smooth and then apply Gel coat If the boat hasn’t been painted. Otherwise paint. Andy at BWT can walk you through it. BTW Love your writing! Next time the Admiral scowls at me for docking by brail I’ll just say it was a PPP!
Maybe I should license out the PPP thing? Hmmm.
Maybe I'lll get a better idea after a little grinding, so to speak. Possibly have to come back and ask opinions.
Thanks for the kind words PB.