View Full Version : Wood Rot Repair

Carl Schaefer
11-28-2004, 09:54 AM
I have several questions concerning the approach to repairs on my newly acquired wood Penguin that I am currently restoring.

There is some rot at the intersection of the chines, stem, and keelson:

I've been told that given the limited area of rot (mostly isolated to the wood I've gouged out in the photo), that I can build up this area with epoxy and some strong filler such as colloidal silica or West System high density (404) filler. Or, alternatively, to use a penetrating epoxy to stabilize the wood, then use a product like System Three's Sculpwood to buildup that area. By the way, the area in question must support the stem knee (removed in the photo).

Also, it appears that the lower pintle or gudgeon (not sure which was fastened to the transom) pulled out at the base of the transom. I've also been told that I can just clean this area up and fill it with a thickened epoxy with high density filler.


However, I'm concerned that the repair will pull out without a doubler installed on the inside:


I would sincerely appreciate any advice from the experts on this forum. I want to balance a desire for repair perfection with the realism that this is a small 12' Penguin that I would like to get on the water this spring. But I also want to make sure that the repairs are permanent and not 'ugly'.

[ 11-28-2004, 03:09 PM: Message edited by: Carl Schaefer ]

11-28-2004, 05:05 PM

That boat's a mess! It looks like fir plywood on what looks like spruce chine-logs and keel. Yulk. As you can see, the spruce rots (cedar wouldn't have). Do you know who the builder is? Wright, Austin, Norton, Beaton were all good builders of wooden Penguins and are usually worth saving. In my experience, home-made boats aren't, in general, competitive for racing (you did say you wanted to race in an earlier thread) and Penguins aren't the best boat for day sailing because one false move on the skippers part and you are swimming with no chance of righting the boat (they tend to float with part of the gunnel underwater). This is neither here nor there but a long time ago, when I was a 16 year old with no sense of my own mortality, I took a Penguin on an extended camping cruise in a fairly remote part of the great lakes and survived so it can definitely be done, it's just that it's a bit stupid unless you fill the boat with float bags and even then ... Anyway.

Further to what I said in a previous thread:

(1) The bow doesn't look all that bad so see if you can clean it out, produce a flat, clean, rot-free surface and epoxy glue-in a dutchman. Use red cedar (white would be better but red is easier to get) because you want it light. Forget the spruce. Remember that the keel/hog/keelson is only 3/4" thick and is beveled to accept the bottom plywood (ie, its thinner than you realize nearer the outboard side of the keelson)

(2) The solution to the transom rot is easy. You replace the doubling piece that goes down the center of the transom and cut dump-flaps in the transom positioned to include all the transom rot. You want dump flaps since they allow the boat to recover from a capsize by being towed by the crash boat. The forward motion causes the water to rush out the rear. Dump flaps are positioned one on either side of the centerline as close to the bottom as possible and each measure about 3x5" roughly. In my efforts to do better on the race course I cover the dump-flap holes with clear wide packing tape because it is light (good) and you can see when you are dragging the stern (bad).

(3) I can almost guarantee that this boat will leak at the centerboard trunk (where it goes through the hog, and in various places along the chine logs and keel. Removing the cenetrboard trunk requires removal of the 3" screws that pass through the keelson into the trunk hogs. Inspect it, rebuild if need be, and refasten with epoxy.

(4) Also, before you sink too much emotional energy into this thing, make sure that it isn't badly twisted. Most penguins this old (1950's) have broken frames and loose gussets. These things have to be repaired/replaced (use cedar for the frames but before you replace them make sure the boat is true. Do this with two long straight "sticks" (I use 8 ft long angle iron but really straight wood 2x4 or something would work too) and place them on the gunnel near the back and another at the mast partners (or slightly further back). Make sure the straight edges are parallel to the nearest frame bottom (measure it with a ruler). Now stand way way back, and sight along the top of the two straight edges -- they need to be parallel. If not, we'll have to talk again! Also, string a string down the center-line of the boat and measure, at each frame, the distance to the outside of the hull on either side of the hull. Make sure the boat is symmetrical and if it isn't, fix it before you reglue the gussets.

All this sounds like a lot of work but it really isn't that bad if you take small bites at it.


Carl Schaefer
11-28-2004, 06:20 PM

I agree the boat is a mess but she is in a lot better shape than she appears in the pix. One top frame is broken but I managed to repair it in place before I removed it to use as a template for a new one. You are correct that many of the 1/4" ply gussets have begun to pull out of the frames, especially on half the frames on the port side. However, I did measure for hull twist, or wracking, but if the hull is twisted, it is not twisted by much, certainly it's not measurable. I was surprised to find that the gussets are nailed to the frames by small round top finishing nails -- why weren't small brass screws used instead?

Thanks for help in identifying the wood used for the keel and the chines. I suspected spruce but was not quite sure.

I used to own a Thistle so I am familiar with capsizes and how difficult it is to bail these things out, even with dump flaps or bailers installed in the bilge. (But unlike the Penguin, the Thistle had a 70 pound centerboard so it had a bit more righting moment and took a bit more to capsize, I suspect). I had thought of putting in dump flaps but two things come to mind; 1) cutting dump flaps in the area of rot will force me to position the pintle mounts further up the transom where the boat is less stiff -- it seems to me that positioning the mounts down close to the keel and skeg will provide for a stiff and strong pintle mount structure. 2) cutting dump flaps will require me to cut both the vertical doubler as well as the lower, curved, transom frame, which, I think, will require me to "frame in" and around the dump flaps with new doublers to take up the extra stress associated with cutting that area.

Relative to centerboard trunk, I suspect you are right that it will leak. The area is structurally sound but I do intend to work around the area inside the trunk with some epoxy filler to prevent leaks. BTW, what is a "hog"? I'm unfamiliar with that term.

Thanks for all your help,

Wild Wassa
11-28-2004, 06:28 PM
Originally posted by Carl S:
"I've been told that given the limited area of rot (mostly isolated to the wood I've gouged out in the photo) ..."

The delamination of the ply is rot as well. These repairs can be some of the hardest that you will do wishing for longevity. Open the cracks as much as you can prior to flooding with CPES or similar. I'd then use a diluted epoxy to follow, then ram or syringe the fillers in. You will need lots of epoxy in the cracks before using fillers.

I attack boats like this with a wire brush in a drill ... don't be gentle rip into her. You could flood all areas with CPES then. CPES appears to be a good rot stopper. CPES works best after 97% paint removal just in case you can't remove all of the paint.

A new keel strip might be needed, you are allowed + or - 5/8th inch off the Class measurements for a new keel strip. Don't ask me how I know this ... I just do.


[ 11-28-2004, 06:49 PM: Message edited by: Wild Wassa ]

Stan Derelian
11-28-2004, 06:39 PM
Lulworth, I want to thank you. I have a Penguin that I used to sail when I lived in California that had a lot of the same problems as Carl's. I cobbled together repairs with some replacment wood and a lot of Splash Zone, and other goops. Sailed it down there with no capsizing, but now that I am up in 50 degree minus water, a capsize is not a laughing matter. My Penguin needs some more work, and with your comments about righting, I think I will pass. Damn, I enjoyed that boat.

Carl Schaefer
11-28-2004, 06:43 PM
"The delamination of the ply is rot as well."

I'm confused about where you see ply delams -- in the ply siding? If you are looking at the ply on the inside, all that is very old, cracked, and peeling varnish. I've begun removing the varnish from the ply starting at the transom and moving forward; the varnish is coming off nicely with 60 grit.

"I attack boats like this with a wire brush in a drill ... don't be gentle rip into her. You could flood all areas with CPES then. CPES appears to be a good rot stopper."

Thanks for the recommendation on using CPES - I was reading a bit about this stuff on the web today.

"A new keel strip might be needed, you are allowed + or - 5/8th inch off the Class measurements for a new keel strip. Don't ask me how I know this ... I just do."

smile.gif I would love to hear that story sometime!

I don't think I need to replace the entire keel "strip" - it looks to me to be in pretty good shape. There is no rot other than what is near the stem. BTW, given that the keel is 3/4" or so, +/- 5/8" tolerance seems pretty generous!

BTW, to answer David's question prior, I don't know the builder of this boat and have no idea how to find out. I was told by the PO, that he thought it was a Horner but I've subsequently been told that it isn't a Horner. I suspect, though, that this boat was not built by an amateur; there are too many little details that an amateur, like me, would not normally pursue.

Thanks again, Carl

[ 11-28-2004, 06:48 PM: Message edited by: Carl Schaefer ]

Wild Wassa
11-28-2004, 06:56 PM
Originally posted by Carl Schaefer:
"I'm confused about where you see ply delams ..."

The cracks in the paint on the outer hull and cockpit. The moment you remove the paint things will describe themselves very well. Even the finest cracks can be deceptive as to what can be a delamination or the starting off ... fixing is always time consuming and repetitive. The flooding with CPES helps because epoxy likes to follow it in, I find. Please don't think that I was wishing you, the worst scenario for your boat.

"the keel is 3/4" or so, +/- 5/8" tolerance seems pretty generous!"

From the Penguin Class Association's rules. I needed to replace a keel strip once and came across a Penguin site that was doing such a repair. It is the large 5/8th" latitude that I remember.


[ 11-28-2004, 07:16 PM: Message edited by: Wild Wassa ]

paul oman
11-28-2004, 07:37 PM
I rebuilt a rotted out dinghy with similar flaws this past summer. You can get by with just lots of epoxy and inexpensive thickener (or use wood flour if you want to keep a wood look).

If you don't care about a natural finish, then do as I did, a flexible epoxy paint to fill checking, leaks etc.

If you want to stay natural then a low viscosity clear epoxy with a flexibilizer added, followed by a varnish and or 2 part clear urethane with UV blockers (which also will protect the varnish if you don't mind a three coat system).

All easy and inexpensive products (except the 2 part urethanes at about $80 or so per gallon)

I don't generally like using a lot of epoxy on wooden boats, for lots of reasons, but this situation is an exception - it ia at the point where the benefits (safe, sound, waterproof boat) outweight the negatives.

paul oman
progressive epoxy polymers
www.epoxyproducts.com/marine.html (http://www.epoxyproducts.com/marine.html)

Wild Wassa
11-28-2004, 07:56 PM
Originally posted by paul oman:
"All easy and inexpensive products (except the 2 part urethanes at about $80 or so per gallon)."

You guys are spoilt with your low prices, I'd like to pay only pay $80 a gal. I pay exactly double that price US$. As I said you guys are spoilt.


[ 11-28-2004, 07:59 PM: Message edited by: Wild Wassa ]

Carl Schaefer
11-28-2004, 08:05 PM
If you don't care about a natural finish, then do as I did, a flexible epoxy paint to fill checking, leaks etc. Paul, what do you consider a 'flexible' epoxy paint? My desire is to revarnish the interior and the rub rail. I want to repaint the hull exterior with Interlux Brightsides. I intended to use an epoxy sealer, followed by primer, then the Brightsides. Any comments on that approach?

11-28-2004, 09:10 PM

First, I meant center board case logs which are (as I learned it) the large pieces that lie parallel to the trunk and into which the screws are screwed from through the keelson (my typo).

Second, yes, the framing is larger on your boat than mine (mine has a solid red cedar transom, I think that the rules require thicker framing when you have a ply transom. The dump flaps can be above the framing but that won't be as helpful to you as I'd hoped. Still, put in the new doubler, and run a new piece of plywood down it to cover the horrors at the lower part of the transom -- or whatever! Make sure everything is clean and flush, use thickened epoxy as glue and all will turn out well (after filling with epoxy filler) At this stage anything will work well enough.

Third, Because of where he lives, I think that Mr Wassa may not be as familiar with fir ply as you are about to become. I'd bet the "cracks" that we see are due to the infamous fir ply checking problem. By the way, fir ply was the material to use in its day (before Occume) because it was the lightest available.

Fourth, Not to be disagreable but in my opinion the benefits of CPES tend to be way, way, oversold. If you want to stabilize the fir to avoid future checking then, maybe ok, CPES or maybe better in my opinion for this applciation, a low viscosity epoxy like MAS (no endorsement/condemnation of either product) might delay by a bit the inevitable checking. Whenever possible, replace wood with wood.

Fifth, If you've sailed a thistle then you know what you are getting into. You will love sailing the Penguin.

Sixth, Stan, don't dump the boat -- I mean this both ways. True the boat will never be self-rescuing but that's no reason to get rid of the boat. A bit of healthy respect for the consequences of failure to pay attention will help (along with a decent dry suit!).

Sixth, It's great to be talking about the Penguin class come sail in Bristol if anyone out there has a boat or wants to frostbite sail with us.

Cheers, David

paul oman
11-28-2004, 09:54 PM
Carl - you're recoat plan sounds fine to me, but I defer to the real experts on this board....

Back in the 70s I spent my teenage years patching and sailing thistle #154 (still my lucky number!) on Long Island Sound. I even did a mini cruise on it which I wrote up and won Yachting Magazines 1976 Jr article writing contest....

-- RE flex epoxies - as we know epoxies are generally brittle and hard (a good thing to be sure) but they can be made or modified so that they handle expansion and contraction of the subsurface better. Especially useful with wood which if then may have lots of natural flex, in addition to the fact that wood expands and contracts with moisture but epoxy expands and contracts with temperature (like most materials). With the wood and the epoxy expanding by different mechanisms (and at different times) sometimes something has to give......

Just adding solvent to epoxy will make it flexible although it is possible that the solvent will eventually find its way out of the cured epoxy and the epoxy will finally become brittle again.

Try forming a disk of CPES - its about as rubbery as a disk of silicon seal! (that's not meant as a bad thing or as a negative statement about CPES) it is simply the affect of solvent loading in epoxy. Other less volatile things will also increase flex, and certain curing agents are less brittle than others.

The marine market seems a little behind the curve when it comes to considering brittleness (or flex) as a characteristic in evaluating different epoxies.

I'm trying to stay very general and not give anyone cause to consider this a commercial plug. Everyone knows I am in the epoxy business - and I have gotten in trouble on this forum before. So no specific products, web links, prices, or specific recommendations, - just general info that is hopefully only educational


paul oman
progressive epoxy polymers