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Discussion Starter #1
Hello everydoby,

my name is Antoine, I have boat a yacht 6 weeks ago and have just joined the community as I think I will have plenty of questions -and troubles!

The yacht is a 40' sloop built in 1990 in South Africa, steel hull and plywood deck.

Of course I had a quick inspection and got the boat surveyed before we bought it, but the surveyor 'missed' some issues that are quite concerning.

The seacocks for the water outlets for the sinks in the galley and bathroom are quite badly rusted -I admit I didn't spot it during my inspection neither. I had another boat builder to have a look now and he told me I'd better get the boat out of the water and get the pipes knocked out and replaced (with plastic?)

Second, since I have spent some time on the boat know, I've discovered that the plywood of the deck is badly rotten -see photo (not the worst part!). It looks like all the deck on portside is to be changed, and the one on starboard has obviously been redone already. The cabin roof looks fine apart from few leaks.

So, what are my options here? Should I rip everything off and redeck completely or can I just redo the portside up to the cabin side? And it's glassed on top so can I just cut out or grind nicely the area to be repaired, replace the ply and reglass? Oh, and the chainplate that runs along the hull to deck joint has started to rust in the worst area. Will I have to change it all?

And most important, is it something that I can do, in how long and for how much? And if not...?


Thank you in advance for your help and advices.

Antoine
 

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First, strike that 'surveyor's' name off your phone list... As Chuckles said this is not something that can be truly diagnosed by someone sitting at a computer.

This looks like the makings of a HUGE project, but only a local knowledgeable type can ascertain just how much of one it might be.

..Steel hull and plywood deck?? sheesh....
 

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Learning the HARD way...
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Those seacocks scare me. I am not familiar with S Valve, but these do not appear to be proper seacocks.

Haul the boat, and replace them all.
 

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If she's already in the water and has been sailing recently, take her out and sail her some yourself. You need to get some love into the girl before you start spending money fixing everything in sight.
 

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Discussion Starter #6
Hi guys,

thank you for your replies.
The surveyor is a boat builder himself, but yeah, I guess he's been lazy, too quick or just bad, but in any case, if you're looking for a surveyor in NZ, I can tell you which one NOT to go with...

Faster, what's the issue with steel hull/ply deck?

I sailed her already and I am really happy with the way she sails -at least I've got that. I love her already, that will help when it will be time to foot the bill.

So, what is my timeframe here? I am going to get the seacocks replaced as soon as possible, but for the decks? Considering that the top paint is three year old (from what the seller told me), the issue is not new but the deck has held so far. Can I afford few months before the major work? (It's summer here so it would be nice to enjoy it a bit before putting the boat on the ground for few weeks...).

Thank you,

Antoine
 

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Steel hull with a plywood deck....well two things, the steel hull and, well, the plywood deck.
You haven't got a hope in hell of sealing the two. It will be a constant battle between the two materials. I would remove the plywood and replace it with steel.
Looking at the through hulls from my living room, I would be inclined to haul the boat out, cut a big hole in the hull around the old through hulls, re-plate it, drill a smaller hole for a new piece of pipe and then put new seacocks on the ends of those pipes.
Surveyors....they crack me up:laugher
 

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....
Faster, what's the issue with steel hull/ply deck?
Dogship already touched on some of it.. Seems to me if you're going with steel and it's advertised strength and watertightness, why stop at the deck? and do that part in a method that invites issues with leaks, rot, etc etc...?

Pro-steel or not, once you make that call it seems to me that all-metal construction is the way to go, not some kind of suspect hybrid.
 
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Seems to me that a change of the deck from plywood to steel would make a huge change in weight distribution and center of gravity and should not be done without advice of a knowledgable marine architect.
 

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Seems to me that a naval architect would never have designed a steel hulled boat with the intension of putting a wood deck on it in the first place. My guess is that this boat was intended to have a steel deck just like every other steel boat.
Based on what I have seen in the pictures of it, someone has cheaped out in it's construction and finished it with a wood deck and many other sub-par fittings.
 

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Steel boat and cold molded plywood deck. How in the world do you seal the hull deck joint? Perhaps a fiberglass cap covering the joint over the edge of the hull with a ton of gooey sealant in it. Someone here should have a better idea.
 

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Discussion Starter #12
The hull to deck joint is all glassed indeed -the whole deck is, see photo.

Regarding the switch to a steel deck... I would be quite concerned about the weight indeed. My boat has 8mm thick steel below the waterline, 5mm above, and so she's quite heavy already (12 tons). I've seen an ad for a similar boat with steel deck and only 5mm thick steel all over the hull and she weighs the same. So I guess switching to steel deck would imply quite an extra weight.

I attach two more photos of the rotten deck (portside) and the redone one (starboard). Do you think that I can go with just replacing the ply on the portside or shall I do the whole lot?

In some articles and books, they talk about just cutting out the core (ply?) without touching the outer skin (glass?). Do you think it is practical here?

Cheers,

Antoine
 

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Wow.. she looks a lot better on the outside!!

Underdeck is not pretty.. have you checked to see if the wood is actually all soft? Can you push an ice pick or and awl into it easily? What's most concerning to me (based on the interior photos) is that things appear to have been allowed to get very wet for some time - esp down low in the hull - it doesn't look like any sort of coating or corrosion protection was applied to begin with. Where did all that moisture come from??
 

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Discussion Starter #14
I know, she does look good on the outside, this is why I tended to trust the surveyor when he told me she was fine.

The previous owner told me that the paint job outside was done three years ago, so I believe the rot problem is older -and the deck has been holding so far. The steel in the bilge and along the side is painted and in good condition, the corrosion is located at the seacocks and along the long deck to hull plate where the ply has been wet. I don't know is she's been all glassed over all her life or if it used to be steel hull/ply deck with some dodgy joint.

I will try and test the softness of the wood.

Thanks all for your opinions.

Antoine
 

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Re-doing it with wood will not improve the situation.
I guess my first question would be how long do you plan on keeping her and what are your plans for her. Ok that was two questions.
You don't have to use steel for the deck there are many aluminum decked steel hulled boats out there.
Of course aluminum is much more expensive than steel but given that the wood you have has some weight to it and it is water logged and covered with glass and resin the weight difference would be minimal as opposed to using steel.
If you were to use aluminum it would probably be even lighter than what you have now.
If you plan on keeping this boat for a while you really need to consider other options for the deck. Given the steel hull, wood is your worst option.
Knowing who designed the boat or what the boats design name is would help us a lot.
 

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Randy Hines
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Hello everydoby,

my name is Antoine, I have boat a yacht 6 weeks ago and have just joined the community as I think I will have plenty of questions -and troubles!

The yacht is a 40' sloop built in 1990 in South Africa, steel hull and plywood deck.

Of course I had a quick inspection and got the boat surveyed before we bought it, but the surveyor 'missed' some issues that are quite concerning.

The seacocks for the water outlets for the sinks in the galley and bathroom are quite badly rusted -I admit I didn't spot it during my inspection neither. I had another boat builder to have a look now and he told me I'd better get the boat out of the water and get the pipes knocked out and replaced (with plastic?)

Second, since I have spent some time on the boat know, I've discovered that the plywood of the deck is badly rotten -see photo (not the worst part!). It looks like all the deck on portside is to be changed, and the one on starboard has obviously been redone already. The cabin roof looks fine apart from few leaks.

So, what are my options here? Should I rip everything off and redeck completely or can I just redo the portside up to the cabin side? And it's glassed on top so can I just cut out or grind nicely the area to be repaired, replace the ply and reglass? Oh, and the chainplate that runs along the hull to deck joint has started to rust in the worst area. Will I have to change it all?

And most important, is it something that I can do, in how long and for how much? And if not...?


Thank you in advance for your help and advices.

Antoine
If any of that plywood decking can be removed intact, it might be useful for patterns for the steel replacing it.
Save what you can and dont throw the baby out with bath water.....
 

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Mermaid Hunter
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I think you're going to need more help than you will get on the Internet. You can get good information that will help you but someone really has to get a look that is both competent and that you can communicate with effectively.

I am also concerned about the existing thru hulls but I wouldn't run out and arrange for a haul and replacement just yet.

My quick suggestion for a plan:

1. Find a credible and competent engineer that you like and trust who will stay with you for the duration of this project and will work with you for the parts you want to do yourself.
2. Get your engineer to go through the whole boat with you and help you prioritize what needs to be done. If the thru hulls are that bad what else got missed? Priorities: keep the boat floating, get the boat moving, get basic services operating, everything else.
3. Schedule a haul out with the engineer to deal with all the priority issues. Look at cost and decide if you should be back in the water or stay on land.
4. Sit down and schedule what gets done when and how.

I can't see much and don't have boat details so I only have a couple of more thoughts: 1. learn to weld - it is easy and could readily save you a lot, and 2. research the concept of consolidated sea chests - I think the idea may make sense for your boat.

Good luck.
 

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How do you handle electrolysis with a steel hull and an aluminum deck?
Well, in a word.....zinc's.
Many large and very expensive yachts are built this way. It allows for a larger superstructure on a comparatively small hull without compromising stability.
 

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Glass covered ply decks were once common on steel hulls for weight saving. Adhesives like 5200 can seal them together.

They built racing boats that way in Europe 50 years ago and they didn't even have 5200 type adhesives.
 
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