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Strip plank construction


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Hi all,

 

Am looking at purchasing a boat with a construction that's new to me, and would appreciate any thoughts. It's single strip planked kauri, glassed on the outside and appears to be evadured (epoxied) on the inside. Not sure about fasteners but potentially riveted. 

 

She's late 1970s and  seems very well built.  Pics belowbilge.jpgfwd berth.jpg

 

 

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Design? Builder?

The ribs will be steam bent fastened with copper nails and those are "roves" you see on the inside of the ribs, the end of the nail has been flattened over them.

Key question is the planking edge glued? Bit unusual, but not unknown, to be glassed on the out side but not inside.

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Well known kiwi designer (don't want to interest others in the boat right now!) and built in a Whangarei yard but owner unsure which.

 

Planking is definitely edge glued. 

 

Just learned what a rove is - cheers!

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Bit of a green hue in that shot so most probably bronze keel bolts pretty easy to identify.

Edge butt and glued strip plank we have one, built 1960s no glass bloody strong boat.

Got well smacked in the marina by some twit and although the force clean snapped a interior shelf hull never cracked.

Timber boat built in Whangarei ? may have been Smiths Boatyard.

Not uncommon to be glued with resorcinol which is a damned strong and durable timber adhesive.

DEB2AD57-0797-465B-95F3-D47039882CDE.jpeg

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I'm not familiar with edge glued kauri, but we've got a double diagonal kauri with a glass skin, of about that era, launched '85, but was 7 years in build (home build in the BoI, a mandarin grower keeping himself busy between pruning and harvesting).

We absolutely love kauri with a glass skin. There is nothing about the construction spec that would be of concern (i.e. not a carvel planked boat). Obviously the usual caveats of age, condition and maintenance.

 

Not knowing what boat and designer, but based on the basic heritage you could be on to a real gem of a boat.

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Those ribs do look quite widely spaced.

352B04C4-D30E-42ED-893E-16482DBD4762.jpeg

Ours are at 150mm centres as hull is old school design and very round and curvaceous like a woman.

Bit of roving going on here.

He would be knackered after that lot and that little stool better not give way.

 

 

 

D0DA8B88-7C61-4A3A-A9F6-86480E2E9A86.jpeg

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That's all really helpful. I've been on plenty of Dbl diag kauri boats but have never seen this construction before. Those widely spaced ribs did catch my attention.

 

The keel bolts definitely look bronze so not so concerned there.

 

The other thing with this boat is some tired looking teak decks. I know the general concerns and issues people have with them but these are still watertight but appear layed very tightly together. Is that normal? In terms of recaulking, should we be thinking about routing a small groove between planks?  

 

20190414_161559.jpg

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Makes no sense to have ribs attached using rivets n roves in an edge glued strip planked boat. Why not just glue them in, if they were needed at all?

 

Where'd the water in the bilge come from? If it's edge glued strip, and it's not coming down the mast, where's it coming from? Glued strip should be dry as a bone.

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Looks like one of Reid's Herreschoffs. He used to build them above where RDM is now. Unusual to glass over strip plank that requires corking? I would have thought the glass would crack over time.

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A lot depends on the execution of plank fitting.

Edge glued is inherently stiff fore&aft owing to grain orientation.

But, imho, requires complete encapsulation for long life as is not carvel system.

A parallel alternative to (dbl diag/fore an aft)but with no rivets.

 

My boat was edge glued with resorcinol and nailed edge wise to preceding plank. Poorly executed as resorcinol requires

very close fitting and high clamp pressure. Laminated frames were all that kept it together as was not glassed.

Pumped water when pressed!

 

Re- planked with old growth 1/4 sawn kauri & epoxy to old frames as a former.

Glassed over with 760gms triaxial to Gerr's "Elements boat strength". ( Sglass/epoxy)

Removed frames, and glasssed inside with same, and fitted stations/bulkheads to DG's scantlings.

Filleted & tabbed.

Deck was built with balsa/epoxy out of reserected old mold.

She be stiff now. - [i bet!!]

And, 4500kg on travel lift! 

Expected heavier.

That's a pretty extensive rebuild!! holy crapoli!

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The other thing with this boat is some tired looking teak decks. I know the general concerns and issues people have with them but these are still watertight but appear layed very tightly together. Is that normal? In terms of recaulking, should we be thinking about routing a small groove between planks?  

 

attachicon.gif 20190414_161559.jpg

They look too thin to router. Based on the teak being warn back to the bottom (or near to) of the calking groves. You need a groove of reasonable depth for the calking to hold in, otherwise it just rolls out under foot.

We had the same looking teak decks (teak over ply). Weren't leaking, as in not leaking into the boat.

After much hand ringing and research, we ended up ripping it off and replacing with glass over ply.

We did have the odd patch of rotten ply under the teak. Typically around deck protrusions, but the odd patch where water had gotten under the teak and caused an issue over a larger area. The sooner you take the teak off, the less issues there are to deal with.

You'll find that routing and re-calking is a fairly intensive job in itself (its a challenge routing straight, and getting around protrusions, fiddly bits etc), and just re-doing the deck isn't much of a step further for a far better outcome (although it is a significant job)

It is a fundamental problem with boats of this age. Teak decks have a finite life. Sorry.

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Roved ribs are a integral part of old school style construction.

Used widely before epoxy came on the scene.

Modern strip plank does away from that and glass shearing adds stability as well.

Teak decks look very unloved and the rebate is almost run out from wear.

You need sufficient teak depth to allow for the rebate to be re routed for sealant and the fastenings can be countersunk and plugged.

8mm would be the minimum.

Worst thing one would do is to take a sander to that deck to regain that flush look.

Ridges and grain grooves are like grip tread????

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How close the ribs are and general scantlings are often a result of purpose as well as the designers style or builders approach.

Coastal cruiser racer lighter than a purpose built ocean boat, for example. Our boat is 4 skin to 1 inch thick, couple of stringers, no ribs. If you ever want to see belt and braces have a look on Quicksilver. Brin Wilson iirc, she has everything. Built to ocean race in anything.

How thick is the hull?

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Thanks for the intel on the decks. It's as I suspected. I guess we just build in the time and cost to get the decks ripped off sooner rather than later in any offer we put forward. Just a question - in checking out the underlying plywood (which appears very sound) does a moisture meter give a very reliable indication?

 

I'm not hearing any huge objections to the construction. I agree that not having epoxy on the inside would be a show stopper but it appears well sealed. 

Not sure of the thickness of the hull. 

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Thanks for the intel on the decks. It's as I suspected. I guess we just build in the time and cost to get the decks ripped off sooner rather than later in any offer we put forward. Just a question - in checking out the underlying plywood (which appears very sound) does a moisture meter give a very reliable indication?

 

The problem with using a moisture meter is it only checks the spot you put it. You are looking for isolated patches of damp / rot. That and you have to force two prongs into the wood, which leaves holes everywhere (prob not acceptable if you haven't already paid for the boat).

My father (who originally purchased our kauri log, and has had a long career in the wood / timber industries) listens to the sounds of the wood when knocked. A dull or flat sound indicates soft wood. A 'knock knock' sound indicates good wood. His preferred tool is a big old screw driver (uses the rounded end of the handle, not the pointy bit). You can use you knuckle, but it gets sore after a while.

 

I've seen boat inspectors do the same thing. They use a small hammer with a rounded head, and walk along 'tap-tapping' the hull every 10 cm or so, with their ear close to the hammer. If there is a rotten bit, it sounds completely different, you don't need much experience to tell. If its really rotten, you hammer / knuckle / screwdriver with leave a hole or go through it (i.e. fairly obvious). The art is the bits that are a bit dodgy but not stuffed.

 

Works well on houses with timber window frames as well....

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If you are serious about the boat engage a experienced old school wooden boat surveyor.

There are surveyors and then there are surveyors.

Listen very closely to what he says.

If those decks are shot and have rot issues it will surface in the survey.

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Thanks guys for this. This boat is not in Auckland or anywhere within easy reach of a good surveyor, hence the desire to check out as much as possible first.  Definitely intending to tap as much of the decks as possible from above and below.

 

Thanks for the offer of the meter lateral, I'll give it some thought. It looks like a great solution. 

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Thanks guys for this. This boat is not in Auckland or anywhere within easy reach of a good surveyor, hence the desire to check out as much as possible first.  Definitely intending to tap as much of the decks as possible from above and below.

 

Thanks for the offer of the meter lateral, I'll give it some thought. It looks like a great solution. 

HaHa dont start doing what my Grandfather did,I was very interested in a particular yacht,price was right she looked right she was on the hard and next thing hes got a 4 inch blade out poking here there everywhere,"the only thing holding that sh*t together is the worm holding hands"

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