Cold-moulding vs. Fiberglass sheathing

Par, I apologize if I offended you. I was under the mistaken impression that BoatDesign.net was created so we could state our own opinions. My opinion is based on my experience, yours is based on your experience. That doesn't make either of them invalid. It only means that the people I dealt with didn't do it right. Obviously you did. I have been told by various people over the years that if you achieve a near perfect mechanical bond between the glass and wood that it will survive very well and and last many many years. I have personally never seen a boat that achieved that. That doesn't mean they dont exist.

Of course my experience is biased because I spent 25 years helping people who had problems with their boats. People didn't come to me who didn't have problems. It makes a person a little cynical because like a cop, you only see the bad guys. My experience with my own sailboat that had been badly glassed over didn't help any. As I am sure you know grinding off all that glass is not a pleasant experience.

I am perfectly happy to agree that if done right a fiberglassed wood boat wood survive very well. But it has been my experience that most DIY boat owners don't have the experience or expertise to do it right. I am certain there are professionals like yourself who do. In fact I have spoken to a few of them over the years and they agree with you that it can be done and that there are lots of boats out there sheathed with glass. In fact when I was at the Wooden Boat Festival a few weeks ago I was surprised to see how many of the brand new boats were being glassed.

However I don't think it is irresponsible to tell a DIY boat owner "don't" If they still want to do it, I would tell them have a pro who knows what they are doing do the work.

I would give the same advice to someone who wanted to wire their boat for 120 V AC. Or who wanted to install a new engine and fuel system. (I do not mean a repair or upgrade I mean something completely new and different from what they currently have, like switching from a I/O 6 to a big v-8 jet) These are things that are better left to a professional. And I think glassing a wood hull is best left to someone like yourself who has a good track record.

 

The very same "incompatible structural properties" resin that will bond a 'glass fabric sheathing to a wooden hull, is the very same "rigid inflexible" resin that will adhere a wooden veneer to the same wooden hull. If the thermoset plastic resin used to bond a veneer sheath is sufficient, what isn't when the veneer is substituted for another material, such as fabric? The adhesive is the same, just the covering material is different. The same is true of wedge seam repairs, scarffed planks, sistered repairs, strip planked sheathing and a few other, less then ideal methods of "tightening up" this old Luke. There are fabrics and resins that will have the flexural modulus and tensile elongation necessary to work well.

At 52 years, the planking, particularly below the LWL, is likely well past its serviceable life span. I work with planking like this all the time and it's usually useless to try to save it. Multiple refastening, egged out fastener holes, rotten fastener holes, hull distortion, panting at every joint, etc., have taken their toll on the structural elements of the yacht.

Frankly, the planking is probably the least of the yacht's big issues and typically the last thing I address, when bring an old gal back to useful service. The planking can only hold on to what is provided, which is likely full of tension cracks and out and out broken frames (judging from the planned replacement the original poster mentioned). This kind of movement is indicative of other, bigger problems then weeping planks and mashed caulk seams.

As those that work on these types of builds can easily confess, when this amount of movement is permitted, even for a short time, a cascade of "load transfer failures" occur. One broken frame not quickly addressed, can not bear its load, so near by frames, planks, butt blocks, faying surfaces and structural members have to step up to their new burden. They now become stressed, eventually beyond their own limits and the downward spiral begins.

Addressing these types of issues can be very difficult, even for the professional. I've cursed many a boat in my day. Unspeakable adjectives that would make the saltiest sailor blush. This said, very few owners can afford a repair route, that will address this kind of under taking. Which leaves us to sheathing schedules.

Long gone (unfortunately) are the days when an owner would wipe the morning dew from the bright work, because they knew how much effort it would save. They're lucky to have a spare fuel filter aboard and SeaTow is usually just a call away. I'm not suggesting Chris is like this, quite probably isn't or he'd have unloaded the old gal some time ago. He, like most of us is a bit different (hard headed by the ones that know us) and wants to do as much as he can, maybe getting her "right", even "Bristol" possably. This is admirable.

Sheathing a carvel hull with anything can be problematic. Wooden veneers are a well proven choice, though tedious and requires a fair amount of skill to apply. Strip planking is easier, adds more weight (offset by additional girth somewhat) and allows more smoothing possibilities. C-Flex would be really heavy, add considerably to the goo factor and fairing issues and leave you with a plastic hull shell, surrounding a wooden hull shell, which is difficult to do properly and expect long life. A biax sheathing would have the elongation necessary, but the sheath would need be unnecessarily thick and the structure very sound or it will sheer. Possibly one of the high tech fabrics (Xynole, etc.) would serve, but again would need to be heavier then required and a stiff structure insured.

Since Chris doesn't want to perform the needed plank repairs (read wholesale replacement), a stop gap or slightly longer type of repair is suggested. The life span of the yacht will be short, before more extensive repairs or rebuild is warranted, but he'll be able to have his cake.

The decision to a type of sheathing is a tough one. The epoxied fabrics will cause issues and make removal very difficult, but since the planking is done anyway, it can be hacked off without regard (so much for templates though). In this vain, over a decade of service can be gathered, but the rebuilding to follow will be extensive. Wooden veneers can provide a generation, maybe more sailing time, with the future rebuild being troublesome, but not as bad as a fabric sheathed hull. Rebuilding a 72 year old yacht (after the stop gap repairs have worn out) is a big job in any regard, so saving yourself or the next owner the most issues as you can may be important. If Chris intends to ride this Luke until it dies under his feet, then a thick fabric sheathing makes a lot of economic sense, as there will be no future rebuild, so let it run until it drops.

In the end, the choice will cause lose of sleep and much head scratching. Each avenue of pursuit for repair, has its pitfalls and advantages. These must be weighed with the needs of the owner, his budget, skills, schedule, plans for the future of the yacht and the overall serviceability of the vessel. Honest answers to self imposed question Chris, will be the only way you can arbitrate the re-launch of your Luke. You can look in terms of years (how many do you want to have with her), dollars (how many do you have to spend), time (how long can you keep your other half convinced you'll fix her) or righteousness (what is good for the old girl).

Best of luck . . .

 

Great article on page 60 about saving Trumpy yachts. http://www.proboat-digital.com/proboat/20071011/

Pericles

 

Thanks all for your feed back on the direction of my boat, especially PAR who has really put things in perspective. My problem is that I'm an idiot, and I have gotten myself into a project that I wasn't ready for at the time. I bought a glassed over beautiful boat without realizing the extent of repairs she would need. Should have gotten a survey. I really did want to keep her wood after stripping the fiberglass, but after having a pro look at her and telling me I would be looking at $50,000 to go that way. He suggested cold-moulding at that time, and showed me how to fix frames by scarfing in and laminating new ones in place. I am over 2 thirds done and will have completely refastened with bronze. I can't believe how bad the frames were. Most everyone broken and barley hanging on. I am now at the engine and have to figure out how to lift the motor out (or slide it forward enough) to
fix that area. My goal is to put $10,000-15,000 more into her and sheath utilizing the best possible method/proper professional help to have a boat I can cruise into retirement.

Geeze, I started this thread a couple years ago and didn't want to start a great debate then. One good article I found is in Wooden Boat #168 pg 40.

Also, please check out my pics. I will have to post some recent ones soon.

 

PAR, I just joined this forum because of this thread. I just bought a 1961 Knutson K-35 yawl that had been C-Flexed in 1994 down in Florida after being refastened and dried out for about 3 months. She's still a very dry boat but she has a plank in the engine bilge with a soft spot on the inside. The soft spot doesn't go through the plank and I'm scratching my head over how to fix this. Should ream out the soft wood and soak the rest in wood preservative before doing an epoxy fill, then sister some epoxy strips over the inside of that plank or what?

 

Welcome aboard Charlie.

A decade and a half is about the time you'll start to see the wooden structure, encased inside a plastic one, showing visible signs of break down (assuming a sound wooden structure to start).

Invariably, moisture gets between the plastic and the wood, then the trouble starts to grow (literally). By the time you see it on the inside, much larger affected areas, yet unseen are looming, soon to start cropping up like dandelions in the spring. Lest hope you've gotten lucky.

To fix your "soft spot" you can just hack out the mush and grind back to good solid wood and epoxy in a Dutchman. Wood preservative is useless on a repair like this, as the whole of the faying surfaces and Dutchman will be embalmed in goo, which bugs and rot don't find particularly tasty. Once you've gotten the rotten wood out, dry the area. You can speed this up with a 100 watt bulb (placed close to the work) and a small fan to move air through, promoting evaporation, a heat gun (though your wrists will get sore quick, fanning the gun across the work and can start fires if left unattended), acetone will remove a fair amount as will alcohol. Just plan old time will work too.

With the wood dry (less then 15% moisture content) slather on the goo and Dutchman. You could use fabric in this repair instead of wood also, just build up a reasonable thickness and insure good contact.

 

Thanks PAR.

 

C-flex Sheathing?

I Have Read These Comments With Great Interest And Signed Up To Gather All The Info I Can Re: C-flex. I Am Looking At Doing This To My 50 Year-old, 75 Ft, Chesapeke Deadrise Hull. This Vessel Lost It Its Certification In 1996 When The Owner Just Blew It Off And Took The Boat To The Bahamas. Now I Want To Recertify The Vessel For Passengers And Have Been Told By More Than One Authority (marines Surveyors) That The Only Method The Coast Guard Will Accept Is To Apply C-flex Sheathing (they Hate Old Wooden Boats Especially Deadrise Designs). Supposedly The Flex Considerations And Concerns Of Separation Of The Laminate Is Overcome By The Generous Application Of 3m 5200 Between The Hull And The C-flex Sheathing Planks. This Makes Complete Sense As I Do Know How Tenacious Yet Flexible 5200 Is. However This Does Not Answer The Issue Of Water That Is In The Hull. Invariably Water Will Collect In The Bilge From The Shaft Log Or Other Means. Can This Eventually Saturate The Wood And Cause Delamination Or Fungus Rot From The Inside Out? Should One Seal The Inside Of The Hull With Epoxy Or Polystyrene Resin To Seal It? Expoxy Coating Seems Logical To Me Becuase It Could Saturate Really Dry Wood. Is There A Permanent Fix To This Issue. Even Total Fiberglass Hulls Can Saturate With Water And Delaminate Somewhat.

 

Chris,

Your statement that "many of the sisters done have been epoxied to the hull", leads me to another method you may be interested in, and that is splining.

Simply put, it invilves cutting the original seam and inserting (glueing with epoxy) a wooden piece of spline, to suit the cut. In actual operation, you can buy a splining saw blade to suit your hand power saw, you simply nail on a battern plank as a guide for the saw while you are cutting the seam, and presto the job is done. You then make the spline on the table saw to match.

Sounds easy and it is, but it still takes a lot longer to do it than it does fo me to write about it.

We have done many "restoration" jobs like this in Aussie land.

 

Eco,

Talk to http://www.sintesdesigns.com/id71.html about your situation.

Pericles

 

Pericles,
Thanks. I Have Read This Site As Well As The Seamann Composites Site And The C-flex Manual. Nothing Addresses The Question Of Saturation From The Inside. It May Be A Non-issue Considering The Adhesive Qualities Of 3m 5200. Thanks For The Participation Though. I'm Glad To See I'm Not The Only One Who Stays Awake At Night Thinking About The Problems I Have With An Old Wooden Boat!

 

Eco,

What you have described is the bane of all wooden boat owners. A new (and modern) propshaft seal might not go amiss, plus painting the bilges with flat roofing compound like this:

http://www.diyplas.co.uk/Product.asp?catid=2&subcatid=342

You could consider this if access is relatively easy:

http://www.rubberbond.co.uk/index.php?campaign=adwords&keyword=roof

You should have similar products over there. Some of the water based products are very effective on damp wood. Always test first!!

Update: The very subject. http://www.woodenboatvb.com/vbulletin/upload/showthread.php?t=71429

Pericles

 

Did you ever successfully sheathe the boat and sail it into retirement?

 

I talked to a guy who has been glassing old fishing boats on their last leg for decades, and people who have had those boats and run them hard who have attested that his method works - he does not bother to reef out and spline the seams gaps between planks as many people on the forums and west system say is necessary. He just slathers a coat of 5200 on the sanded hull. Leaves the old cotton in place. Then polyester resin and glass fabric stapled down. Several layers. That's it. Apparently, the 5200 actually bonds better if the wood is damp. Which also seems to go against the current of what Ive read on the forums. Is this legit?

Could you use 5200 as the layer between planking and first veneer of a cold molded overlay?

I am wondering, assuming cold molding over carvel would provide all the needed structural reinforcement needed, even if some of the planks started rotting out from day one or year 10, would it really matter? Could you just keep using the boat indefinitely, as the cold molded overlay is providing so much more structural reinforcement and rigidity?

 

You could, but would be really expensive. 5200 cures with moisture, but not well if the wood is soaking wet. Also, structural reinforcement and stiffness are two different things. Leaky old planked hulls may still be reasonably stiff.