H28 bath - opinions on how long to let her soak?

[Larks]

I'm after opinions and/or experiences in reviving the dried out deadwood on a hull, which in my case is an Australian hardwood, possibly Tasmanian Blue Gum.

I have set up a "bath" under my H28 (strip plank huon pine) to see just how far the deadwood will recover from a couple of years of sitting in my shed. The aim here is to see if I may need to eventually fit some splines to the gaps if they don't show any signs of getting close enough for caulking alone - and if so what sort of thickness I will need.

I am very aware of the risk of blowing off my keel bolts if I do the wrong thing here so I want to make sure I let this "regrow" as much as it is likely to before I open it up again, hence my question is:

How long do you guys think it would take for the deadwood to reach its maximum absorption/expansion?

I had been thinking up to about three months or more and was quite prepared to just set the bath up and leave it that long - or even five to six months???

But of course having set the bath up I am now sure to start becoming impatient to open her up and have a look to see what is going on......which is not really an easy option, mostly because I have salted the water and don't want to have to drain it until completely necessary. I don't have any similar type/age wood to use as a sample to see how it behaves as a guide.

My other question is: how is the timber likely to behave by being soaked, dried out then soaked again and potentially left for another couple of years dry again? Is it likely to lose some of it's recoverability each time the fibres dry out and compress?

Here is a shot showing the extent to which she has opened up along the deadwood:

http://i260.photobucket.com/albums/ii11/Larks_01/P6060073.jpg



http://i260.photobucket.com/albums/ii11/Larks_01/P4040093.jpg

And this is what I have set up for the bath, with ply formed up to form the waterproof membrane against the hull to minimise the water needed and therefore the weight that'd be trying to rupture the membrane:

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0003.jpg

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0004-1.jpg

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0007.jpg

As much as I am hoping someone else here may have gone through this and have some experience in how it worked, all opinions and speculations are welcome!!!:) Should I take bets?

Here's the rest of the refit: http://forum.woodenboat.com/showthread.php?111296-H28-quot-Larrikin-quot-rebuild

[PeterSibley]

Hi Greg ,as I mentioned before it seems likely the top section is e.regnans .Shamus could probably send you a sample of demo 4x2 ,it's pretty common in Tasmania .

I'll take a punt at 3 months to swell .This page is of interest .http://www.dpi.qld.gov.au/26_14612.htm

[P.L.Lenihan]

The easy answer,of course, would be to let her soak 'till the seams are tight. But I really know nothing of the particular wood properties on your boat Greg.

So instead, will say simply, I hope she soaks up well and closes tight before you summer returns! Thank goodness for some Guinness to make the wait not seam too long:D


Cheers!


Peter

[Larks]

Yes, sorry Peter, I hadn't responded to you on that but I meant to tell you that most of the hand adzed beams that I built my first house from in Alice Springs were Tassie Mountain Ash/Eucalyptus Regnans and that top piece does seem to have a similar grain, I guess I really need to grind a bit of the darkened outside timber off to see what colour it really is. My beams were a lovely honey colour when dressed back with an angle grinder and shellacked.

[Larks]

The easy answer,of course, would be to let her soak 'till the seams are tight. But I really know nothing of the particular wood properties on your boat Greg.

So instead, will say simply, I hope she soaks up well and closes tight before you summer returns! Thank goodness for some Guinness to make the wait not seam too long:D


Cheers!


Peter

Thanks Peter, I think it will be a few Summers before this one is back in the water - just as well Guiness don't look like going out of business soon!!!

[cookie]

I have been asking myself similar questions as I noticed severe cracks on several parts of my boat as it appears to be drying out beyond the "usual" humidity levels.

If I were you, I would take a moisture meter and measure the moisture% the wood now has. Than work out the numbers for expansion at the desired moisture % and if the beams have swollen to approx that size, I would remove the bath. Ehrr. How a bout a 3 week soak or so, then let is spread through the wood and then another soaking period? Maybe that provides a more equal moisture distribution? Just a silly idea perhaps...
Regarding structural strength: I think (no knowing involved, unfortunately) that the wood does not loose strength as long as you do not loose lignum or see (mini) cracks and checks appear.

[Larks]

Cookie, before I set up the bath the timber was reading about 13-14% moisture content but I didn't take any reading before she started drying out to compare.

[cookie]

Hmmm, are you sure about that percentage? That should be a very nice moisture level to work with. 15% is normal for well painted wood under the water line, according do Dave Gerr.

[RFNK]

Good puzzle Greg! How about running some lengths of different thicknesses of plastic through the gaps and out through the top of the bath, and every week or so you can see whether they've become stuck from the swelling timber? When the thicker ones are stuck you'll know that the swelling is happening and then when the thinner ones become stuck then you'll know that the gaps have really closed up.
Rick

[PeterSibley]

The expansion figure on the page I linked to are interesting Greg .

[Larks]

Hmmm, are you sure about that percentage? That should be a very nice moisture level to work with. 15% is normal for well painted wood under the water line, according do Dave Gerr.

Yes, I actually checked it over a few months starting from just at the end of our dryer winter coming into summer and just before the bath went on, the last five months or so having been quite a wet summer. It didn't really seem to vary more than 1% over that time. The yacht was built in Tasmania so the timber may never have dried as much as it would here when built and I have no knowledge of how it may have been treated before build, ie how green it may have been.


Good puzzle Greg! How about running some lengths of different thicknesses of plastic through the gaps and out through the top of the bath, and every week or so you can see whether they've become stuck from the swelling timber? When the thicker ones are stuck you'll know that the swelling is happening and then when the thinner ones become stuck then you'll know that the gaps have really closed up.
Rick

Not a bad idea Rick, though you have got me thinking now that I could probably just cut a small window into the ply sufficient to be able to feel the gaps under the membrane.



The expansion figure on the page I linked to are interesting Greg
Shrinkage to 12% MC. E. regnans: 13.3% (tangential); 6.6% (radial).

I'm not sure how to use this info' though Peter, the unknown is what stage it was at when it was built and launched.

[PeterSibley]

Shrinkage to 12% MC. E. regnans: 13.3% (tangential); 6.6% (radial).

I'm not sure how to use this info' though Peter, the unknown is what stage it was at when it was built and launched.

I'm assuming it's all pretty dry now ? If the shrinkage figures match the actual percentages on your boat could we assume it was pretty green when bolted up ?

[cookie]

I looked at some data I have here for Mahogany and for each % rise in moisture content, expansion is as follows:
.15% rad .23% tan

rad meaning expansion perpendicular to growth rings, tan is parallel to growth rings.

If you take a wild guess (ie by averaging values of similar looking woods) you will have a value good enough to give an indication of expected swelling.

I would be surprised if the timber swells more than 1.5% in the 13 to 17% trajectory.

[Larks]

I had a look at some of the pieces of hardwood that I've removed and am wondering if they may be what was used in the deadwood.

I have a piece of the sampson post that I have removed at deck level and that does look like Tassie Mountain Ash as Peter suggested (E.Regnans), but a piece of the engine bed I'm still assuming to be Tassie blue gum, though I'm really not sure. I kind of suspect that the sampson post timber is what is used in the top piece of the keel timber in the above pic and whatever is used in the engine beds is in the middle and possibly lower piece??

Here they are to show the colour difference, the engine bed on the left has a second lighter, pinker piece of timber epoxied to it:

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0013.jpg

Their moisture readings were interesting

The sampson post - around 13%:

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0034-1.jpg

And the engine bed around 15 -16% on the darker timber, but interestingly around 18% on the lighter smaller piece:

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0033.jpg

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0043.jpg

This is a pic of a still visible section of the stern piece of the deadwood showing a piece of the prop' aperture that appears to be similar to the lighter/pink timber used on the engine bed. Though I've ground off a bit of surface timber to reveal the grain underneath it is still quite difficult to pick the timber from the colour:

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0017-2.jpg

[Larks]

Here is a section of that strip of stern post from the inside showing the timber as a little lighter (drier) though more like the engine bed than the light blond of the sampson post timber:

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0024-1.jpg

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0025.jpg

And some of the keel timber from inside - it does have the "feel" of the Tassie mountain ash, the moisture makes it a bit hard to pick the colour but their are hints of that blonder colour of timber in the sampson post:

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0018.jpg

The floors seem to be more densely grained but interestingly appear to be the same blond colour, rather than brown, pink or browny red

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0026.jpg

[Larks]

So I've come up with another very basic back yard experiment:

I've measured a few aspects of these bits of timbers as well as another (still mostly painted) engine bed piece which I've also checked the moisture on:

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0058-1.jpg

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0060-1.jpg

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0061-2.jpg

I've marked the measured points with a sawn impression so that I use the same points each time I measure them and chucked the two pieces of test timber in a bucket of salty water, keeping the painted engine bed aside as a sort of "control" to have someting to compare rates of moisture uptake and expansion against.

http://i260.photobucket.com/albums/ii11/Larks_01/DSC_0066-1.jpg

And loaded all of that onto a basic spreadsheet so that I can track it and try and work out an expansion rate or curve.........

[Phil Y]

Those look like big gaps, but I guess at some stage the timber must have fitted. Can't offer any advice, but Ill be interested when the answer presents itself.

[PeterSibley]

A very complete experiment Greg , I wish you luck and lots of swelling !

[JoshuaIII]

With those big gap of 2cm... Wouldn't been better to tied up all those bolts to close the maximum possible before soaking everything up? I mean at 15%MC it's what people use for brand new construction... So it won'T blow the bolts away!

[Larks]

With those big gap of 2cm... Wouldn't been better to tied up all those bolts to close the maximum possible before soaking everything up? I mean at 15%MC it's what people use for brand new construction... So it won'T blow the bolts away!

What you say would "seem" to be correct and I'm confused by the moisture readings - they may just be surface readings (I should try and find a a moisture meter that'd measure right through the timber from one side to the other). But she was originally closed up, so I'm really wanting to see just whether she will do the same again, or at least come close to it, before I do anything like fitting splines and snugging the bolts up.

[hanleyclifford]

Why don't you keep that wood soaked up with linseed oil?

[JoshuaIII]

I would be surprise that the middle is more dry then the outside, as air dried wood dry by the outside first.
So if it's write 15%MC at the outside, expect more inside so not more swelling there...

I don't know, personally I would prefer to have a nice tied fit there, then a loose fitting barely touching...
But that's me, it's not my boat and it's all your choice which I respect. I've been proved wrong before ;)

And as you said, if it was touching before... There is hope! :D

[purri]

Linseed oil in any form is a permeable membrane and barely slows the takeup of water. I'd suggest a minimal EMC of 22 before snugging up any bolts/setscrews. BTW some of the examples look like blue gum to me. The 2nd last pix looks like spotted dog to me.

[Larks]

Why don't you keep that wood soaked up with linseed oil?

Hi Hanley, I did try linseed a while back in some areas and on some test wood without any discernible success, as with Ethylene Glycol, which looked positive on some bench tests but didn't transfer to the deadwood.

[PeterSibley]

I think I can see some splines in your future Greg ! Big ones .

[hanleyclifford]

Hi Hanley, I did try linseed a while back in some areas and on some test wood without any discernible success, as with Ethylene Glycol, which looked positive on some bench tests but didn't transfer to the deadwood. The (raw) linseed oil must be cut almost 50/50 with something like green cuprinol or kerosene or even diesel. I like the apparatus you have built (I have a very similar boat). Fill that bath up with the mix and you'll get results. Edit: My boat can be seen at http://www.moyermarine.com (my albums). I just posted a new picture of her deadwood and partial hull.

[shamus]

I think probably blue gum, but could possibly be stringybark (E. obliqua last time I knew, but they keep changing the names). I should think it was assembled green. I note the comments above about building with 15% moisture content. This would rarely be done here in Tassie. Blue gum is a good long lasting timber for keel and deadwood, but it does move around a bit with moisture variation. Therefore, since our boats live in the water all year it is better to build green, throw in the water and keep it wet. I suspect you'll see a noticeable adjustment in dimension in a month or so!

[Larks]

I think probably blue gum, but could possibly be stringybark (E. obliqua last time I knew, but they keep changing the names). I should think it was assembled green. I note the comments above about building with 15% moisture content. This would rarely be done here in Tassie. Blue gum is a good long lasting timber for keel and deadwood, but it does move around a bit with moisture variation. Therefore, since our boats live in the water all year it is better to build green, throw in the water and keep it wet. I suspect you'll see a noticeable adjustment in dimension in a month or so!

Thanks Shamus, that is invaluable!!! Especially because it also answers the question that I'd been asking myself (and may have mentioned on my other thread early on) about why it seemed to have been built out of green timber. It makes a lot of sense now. I'll give it at least a month before pumping out and opening it up again.

I'm thinking now that once I have it back as far as it will go, it will be worthwhile getting all of that caulked and painted then rebuild the bath for the duration while I fit her out and build the decks, cabin sides etc.

[Duncan Gibbs]

I would also be getting a bag of salt into the bilge and into the bath as well Greg as both E. regnans and E. globulous are are not well rated in-ground, suggesting they rot easily. Either salt, or a copper based fungicide. FWIW globulus has a 12% tangential shinkage, while regnans is 13%. I think your idea of getting these timbers wet and keeping them that way will be essential.

Just don't use fresh water.

[RFNK]

To be honest, I don't think I'd take this approach. I'd just leave it all dry while you're doing all the other work on the boat then put caulking or soft timber in all those gaps, paint it all up with primer and antifoul and put it back in the water. It's all going to swell back up - I don't think there's any doubt about that. Then, take it back out of the water after a few months and tidy it all up. As far as the keelbolts go, it's easy enough to put them in fairly tight but have soft timber washers under the nuts. As they start to pull into the washers, just ease them off a bit and keep replacing the soft washers until there's no sign of further movement.

I think the bath etc. is just going to be in the way while you're doing all the work, any damage caused by drying and shrinking has already happened anyway, and you could be inviting rot problems elsewhere from the humidity associated with having the boat sitting in a bath for so many months.

I know at one stage you were considering sheathing too. If you go with that then you will have to fill all the gaps anyway and you'll want the hull to be as dry as possible.
Rick

[Larks]

To be honest, I don't think I'd take this approach. I'd just leave it all dry while you're doing all the other work on the boat then put caulking or soft timber in all those gaps, paint it all up with primer and antifoul and put it back in the water. It's all going to swell back up - I don't think there's any doubt about that. Then, take it back out of the water after a few months and tidy it all up. As far as the keelbolts go, it's easy enough to put them in fairly tight but have soft timber washers under the nuts. As they start to pull into the washers, just ease them off a bit and keep replacing the soft washers until there's no sign of further movement.

I think the bath etc. is just going to be in the way while you're doing all the work, any damage caused by drying and shrinking has already happened anyway, and you could be inviting rot problems elsewhere from the humidity associated with having the boat sitting in a bath for so many months.

I know at one stage you were considering sheathing too. If you go with that then you will have to fill all the gaps anyway and you'll want the hull to be as dry as possible.
Rick

I did debate this back and forward quite a bit before going down this path Rick, there's merrit either way but as this is (for me) mostly a project about learning I decided the exercise to see just how well this would close up and over what period is worth pursuing. I'd also decided, as the hull is huon pine, to do everything I can to avoid sheathing the hull now, (however if I do want to go down that path for some reason I know how long it will take to dry out again:D).

No problems re salt in there Dunc':
mostly because I have salted the water and don't want to have to drain it until completely necessary

[Welding Rod]

Let it soak a while then look at it.

[hanleyclifford]

The wood will soak up thin oil a lot more readily than water, and the oil is much healthier for the wood.

[JoshuaIII]

The wood will soak up thin oil a lot more readily than water, and the oil is much healthier for the wood.

+1 throw some hot pepper, a bit of garlic,some spices and you have a always ready huge pot to marinade your fish and meat before cooking! Cooking on old wood piece would be even better ;)

[Paul G.]

To me you are over complicating things.

That amount of shrinkage in the deadwood doesnt seem right. I would tighten her up, then soak. I bet she wont take up those gaps fully again.

[Larks]

The wood will soak up thin oil a lot more readily than water, and the oil is much healthier for the wood.

I didn't know that Hanley, but it will be quite a while before this is ready to be relaunched so I'll have time to redo this exercise with linseed oil as you suggested. I do have some cuprinol at home (is the "Green Cuprinol" that you suggest in any way different?) so will experiment with cutting the linseed oil with that and seperately with kerosene to see how they go on some blue gum. It will be interesting to see if what difference there might be in the expansion against the other little experiment that I'm running at the moment.

I did research the idea of cutting linseed oil with kerosene (parafin oil) a while ago, as suggested in one of the older boat building books (I forget which one) but there seemed to be quite a mixed reaction with a number of people concerned about the increased flamability of the timber if soaked in kerosene. I couldn't come up with a reasonable argument against that so I'm interested in the cuprinol idea.

I might just have to have a "flame" test at the end of the experiment to see if the kero' actually does make the timber any more flamable..

[wizbang 13]

I think I would have ripped that keel down with a sawzall and made 3 or 4 planks from it, working around and up to the bolts.
Or, cut a series of kerfs into the keel. Then, locked it up with epoxy, stabilize it.
It looks like too much shrinkage to me too.
And what's doing with that garboard, it is a carvel plank?
The combo of a large timber keel and strip planking is cwazy!

[Larks]

To me you are over complicating things.

That amount of shrinkage in the deadwood doesnt seem right. I would tighten her up, then soak. I bet she wont take up those gaps fully again.

You may be right Paul, but the shrinkage has happened one way or another and going on Shamus' knowledge of boat building practices in Tassie his advice on the reasoning seems quite acceptable. What you suggest re tightening the bolts seems contrary to all previous experienced advice that I've heard on dealing with keel bolts on wooden boats and it isn't something that I'm willing to bet on myself.

I am well aware of an incident on the 90' yacht Emma where just such a thing was done. The keel bolts were snubbed up, the yacht put back in the water, the timber took up back to where it was originally - more than had been expected by the owner and guys working on her, the silicon bronze bolts snapped under the pressure and the keel fell of.

I'd rather that didn't happen to this yacht and I'm a strong advocate of time taken in preparation is time well spent, particularly while I have the luxury of that time to play with in this stage of the resto'.

[Paul G.]

Possibly true,

But timber doesnt take up as much as once it has completely dried out and those are MASSIVE gaps. I would almost be tempted to rebuild the deadwood, its got to be easier than fiddling around with baths moisture meters and guesswork. I had my boat out for 5 years and it opened up zero on the deadwood Z-E-R-O! The planks were another story they opened about 1-3 mm with quite a few not at all. So I would say that your boat has some special needs

[Lucky Luke]

Hi Larks,
I think (?) I had already commented on your problem when you mentioned it in another thread, is that right?
Anyway: what I see now just shows that same thing: this wood will NOT get back to the volume it had when but into this boat as it was green wood, and wood NEVER get back to their original dimension (either moisture content) of when they were green, no matter how long they may be in water, linseed oil or other miracle salad sauce. There was sort of heavy caulking there, plus nasty fiberglass to hide it/ keep it in place, and whatever you do besides splining or wood replacement will be useless.
We do not (or should not :rollleyes: !) build boats with wet, green wood. Keel bolts, caulking, painting: all that done with dried wood, sometimes by years under cover, plus years with the boat under construction in the yard (Note: not excessively dry, never!: down to 12% is still acceptable, less is bad! As well: one do NOT over-tighten keel bolts, neither over-tighten the caulking: just normal boat-building practices).
So: why worry, and why insist on this "bathing" ????:confused:

[Larks]

So: why worry, and why insist on this "bathing" ????:confused:

Hi Luc', the easiest answer to that question is simply so that I can see what will happen. This really is mostly about learning for me and as I have the time to let it sit in a bath it is no great imposition for me to do so. The bonus to this possibly futile exercise though, is the exposure to so many terrific opinions on the subject, all of which seem to me to have great merit in the right circumstances, (other than perhaps -sorry Paul- tightening up the keel bolts). I also hope to be able to contribute to this wonderful font of knowledge by whatever I may or may not gain from the experience if someone comes up with a similar circumstance in the future.

I do agree with you and Paul that it won't swell back to what it would have been as green timber but I know that it will come back to some degree and I simply don't know just what degree to expect so was wondering how long anyone should expect it to take for that maximum "come back" to take, ie days, weeks months???.

Although Shamus' advice re the practice of building with green timber in Tassie does seem to answer some questions in the instance of what I have experienced here, I really don't know the history of the build, how green "green" may have been and what moisture content this timber went into the hull with.

The heavy caulking that you saw was between the garboard and keel timber, but those big gaps that you see in the photo had very little of anything between them at all, I'll see if I can find another photo for comparison when I get home this evening.



And what's doing with that garboard, it is a carvel plank?
The combo of a large timber keel and strip planking is cwazy!


Wiz, the garboard is part of the strip plank build, ie glued to the next 1" plank above it. I have seen this larger garboard plank in a number of strip plank builds and in books on the subject, is it not something that you'd expect to see normally?

Also why so "cwazy" re the keel timbers and strip planking?

[wizbang 13]

Books on strip planking, Hmmmm. Books are my kryptonite.
I have not seen a carvel gbd. on a strip boat like that. Well, until now. And sure would not build one.
The "cwazy" part of large timber and strip plank is that one is stable and one is not. A glued boat should have a glued keel and deadwood.
It almost as if the boat was laid out for carvel and was switched over at the last minute.
anywho, it IS interesting watching what is happenning there.

[RFNK]

It certainly will be interesting to see just how much it does swell back up, and how long it takes. I, for one, am grateful that you're sharing this with us!
Rick

[Larks]

Books on strip planking, Hmmmm. Books are my kryptonite.
I have not seen a carvel gbd. on a strip boat like that. Well, until now. And sure would not build one.
The "cwazy" part of large timber and strip plank is that one is stable and one is not. A glued boat should have a glued keel and deadwood.
It almost as if the boat was laid out for carvel and was switched over at the last minute.
anywho, it IS interesting watching what is happenning there.

I was unsure about the garboard myself when I first saw it so went looking for the reason, here is one reference that seems to encompass pretty much all that I fouund:
http://books.google.com.au/books?id=JrslZpcyuxYC&pg=PA74&lpg=PA74&dq=strip+planking+garboard&source=bl&ots=4mtbjRfk99&sig=CZOXzEj6eXjfjNZ3kaPOCyJUtY0&hl=en&ei=k_fKTTyBlLwD2uKE6wU&sa=X&oi=book_result&ct=result&resnum=2&ved=0CCYQ6AEwAQ#v=onepage&q=strip%20planking%20garboard&f=false

As for the deadwood, you may be right, this wouldn't be the first time that someone has worked hard to get the deadwood all layed down only to have to change their plans for any number of reasons, who knows how the builders circumstances or thought processes may have changed at the time?

[Paul G.]

Here is my take for what its worth;

remove lead, make new deadwood, finish strip planking, overlay with a diagonal of 1/4 inch veneer. glass and go!

Forget trying to fix the existing!

[Duncan Gibbs]

A good many of the Eucalyptus species (scleryphic trees) can shrink and swell with ease. On something with a 12% tangential shrinkage it will swell back up close, if not all the way to it's original dimensions. Many of the gums have amazing tension in the log as well and drying can accenuate this tension. I'd think that a good part of the gap is caused by such a drying/tension combination.

[JoshuaIII]

Here is my take for what its worth;

remove lead, make new deadwood, finish strip planking, overlay with a diagonal of 1/4 inch veneer. glass and go!

Forget trying to fix the existing!

It is a interesting point of view, specially considering that the whole hull is perfectly dry to achieve that right now...

[Larks]

Here is my take for what its worth;

remove lead, make new deadwood, finish strip planking, overlay with a diagonal of 1/4 inch veneer. glass and go!

Forget trying to fix the existing!

:D you and Wizbang just want to create more work for me don't you!! This comes under the category of good advice when you don't have to do it yourself. In practicality there's no need to go to such lengths, other than the shrinkage the deadwood is perfectly sound except for one very small section of soft timber up at the bow and the huon pine at 1" thick will never rot, is as solid as the proverbial brick shyt house (other than a couple of glue lines that I need to repair) so any veneers and glass would be just superfluous.

[Larks]

A good many of the Eucalyptus species (scleryphic trees) can shrink and swell with ease. On something with a 12% tangential shrinkage it will swell back up close, if not all the way to it's original dimensions. Many of the gums have amazing tension in the log as well and drying can accenuate this tension. I'd think that a good part of the gap is caused by such a drying/tension combination.

Thanks Duncan, that's probably the most reasuring thing that I've read here so far. What's your guess on the timeframe to regain as much swelling as it is likely to?

[Duncan Gibbs]

At a guess, three to four months. It would be interesting to see what the grain of each timber is in section. I'd be thinking that the side which sits closest to wher the heart was is the lower side. This stuff is strong... Insanely strong and any tensions accentuated by drying on such a large section will be impossible to synch back up.

[shamus]

I'm moderately confident that this will turn out to be the right thing to do and will turn out OK. I don't know if they still do, but Forestry Tas used to pond blue gum in salt water for use as keels- now they didn't do that to have it dry did they? Wilson Bros used to build those big sailing barges in about a year. The first job being to fell a tree for the keel. How dry is an 18" x 18" keel going to be in 12 months? They also planked green, but promoted a moderate amount of airdrying in the (much smaller dimensioned) planking by hanging every second plank and then planking the gaps. (Good spilers those boys). All this is documented with photographs and interviews with old timers in Gary Kerr's book.
I have a friend who built a fifty foot fishing boat about 30 years ago in Bernard Wilson's yard. He said Bernard told him to build the keel and deadwood wet and never let it dry out. Now this one has dried out, but from my experience a dry piece of blue gum will return to its original dimension, or very close, upon immersion.

[JoshuaIII]

Larks at the stage we are at, I think you should take bet!
I bet a local beer that it will get close but won't fill entirely the gap...
Somebody taking this bet, would sure like to taste a exotic beer paid by someone else :d

[Larks]

Larks at the stage we are at, I think you should take bet!
I bet a local beer that it will get close but won't fill entirely the gap...
Somebody taking this bet, would sure like to taste a exotic beer paid by someone else :d

Difficult to bet against you when you're betting on what I'm expecting myself. My unknowns are the extent of how much the planks will return so that I can estimate what thickness of splining, if any, may be needed (or what and how much caulking to use) and how long to give it to reach it's potential maximum swelling.


I'm moderately confident that this will turn out to be the right thing to do and will turn out OK.

Thanks Sean, I reckon you are right, while it's great to see and consider all of the opinions on the forum here and weigh up all of the pro's and cons, nothing beats your local knowledge

[PeterSibley]

Still watching Greg !

[Larks]

You might be watching for a while Peter, I'll leave it soak for a bit yet before I empty the "bath" and take a look at the results. In my earlier bath set up I had installed a tap and drain so that I could easily empty the bath but that seemed to be one of the leak points (not easy to get a tap to seal into a piece of plastic sheet) so I've left it out of this new membrane set up, so it's not such a quick and easy thing to empty (and I don't want to drain the salt water into the paddock until I need to).

So at the moment I'm just taking some measurements on the test samples at regular intervals to see what rate they expand and if they seem to plateau at some stage, which I hope will then give me an indication of when to have a look at the hull. If I can work out how to, I hope to be able to post some sort of an "expansion curve" (???) here when I have enough measurements to make it worthwhile.

Meanwhile I have now also set up a separate linseed oil and kero V. salt water "expansion" test as well, following which I'll put both samples to a "burn test", to see if the kero impregnated wood is actually that much more flamable than the salt impregnated wood.

[Lucky Luke]

It certainly will be interesting to see just how much it does swell back up, and how long it takes. I, for one, am grateful that you're sharing this with us!
Rick

+1!
....as for the time it will take before it "stabilizes": surely many weeks, but how many months...?

[PeterSibley]

Meanwhile I have now also set up a separate linseed oil and kero V. salt water "expansion" test as well, following which I'll put both samples to a "burn test", to see if the kero impregnated wood is actually that much more flamable than the salt impregnated wood.

Are you taking bets on that one ? :d

It's all very interesting Greg ,it's just a pity the test bed are your keel timbers .I've done quite a few test on different species over the years ( and of course forgotten to write down the results !) but usually milling up samples exactly 100mm wide by 5mm thick,air dry then putting them in a jar of water for various periods,weeks to months .The results are usually similar to Bootle when radial /tangential are factored in .

[Duncan Gibbs]

Just to give you an indication of the tension in Eucalypt timbers as they come off the saw:

http://pic80.picturetrail.com/VOL1913/10058894/20216063/380905188.jpg

If you go to a proper mill they'd "cut" the bow out of the timber by re-sawing the timber, which would be cut to a larger dimension that that I've shown to begin with. Needless to say, on a green piece of timber cut to final dimension, if it's allowed to dry out it will reveal these tensions again. Soak it and they will head back to it green shape.

[Larks]

If anyone is still interested, here is a bit of an interim report on my wetting out experiment that I have sitting alongside my boat bath to see if I can get an indication when saturation and the expansion limit might be reached, as well as an interesting finding re linseed oil.

The time frame is yet a bit short, in this first set of samples only 3 weeks, from 5 May 2011 to today (27 May 11)

I have three pieces soaking in salted water, covered with plastic, a piece of Tassie mountain ash taken from my sampson post; a quite large piece of blue gum taken from the old engine bed and a smaller piece of blue gum from the engine bed as well:

http://i260.photobucket.com/albums/ii11/Larks_01/IMG_0093.jpg

http://i260.photobucket.com/albums/ii11/Larks_01/IMG_0092.jpg

Firstly, the Ash, (I don't have a control piece to compare it with in this case). I have taken four measurements on this one, three across the grain and one along the grain - which is the top line below and which has only changed by approx + 0.05%, the other three have changed by approx +6.2%, +6.5% and +6.6%.

Most importantly, the measurements show a steady growth that has not yet topped out:

http://i260.photobucket.com/albums/ii11/Larks_01/Sampsonpost.jpg

Secondly, the piece of blue gum engine bed. Although I have a few more measurements on this piece, the measurement accross the thin side shows the most change, albeit only a 1.5% increase. The broader side shows only 0.4% and the length measurement shows no change. Despite the smaller numbers, the growth is still steady and not yet topped out:

In this graph, I do actually have measurements from a dry control piece, represented in the bottom line:

http://i260.photobucket.com/albums/ii11/Larks_01/Enginebed.jpg

[Larks]

Finally, I added a third piece to the test bed to include the comparison between soaking in salt water and soaking in a 50/50 linseed oil kerosene mix, as suggested by Hanley:

http://i260.photobucket.com/albums/ii11/Larks_01/IMG_0088.jpg

Again I measured both across the grain and along the grain and included a third dry control piece.

http://i260.photobucket.com/albums/ii11/Larks_01/IMG_0090.jpg

http://i260.photobucket.com/albums/ii11/Larks_01/IMG_0091.jpg

Interestingly, this also being the same hardwood as the larger engine bed frame, in the salt water soak over only two weeks it hs shown a 2.4% increase accross the grain, with only a 0.4% increase along the grain.

More surprising though, the linseed oil/kero soaked sample has shown no discernible increase in either measurement.

In the following graph, the green line is the control, also showing no increase as would be expected, the red/pink line is the linseed/kero sample and the blue line the salted water sample. The pieces are all "roughly" the same size.

http://i260.photobucket.com/albums/ii11/Larks_01/Enginebedframe1.jpg


The main outcome for now though is that I am not yet ready to remove the bath to have a look at what has been achieved.

[PeterSibley]

Assuming the large timber in your keel assembly is ash Greg , what percentage swelling would close the gap ?

[Larks]

Assuming the large timber in your keel assembly is ash Greg , what percentage swelling would close the gap ?

I'm pretty sure the large timber in the middle is blue gum and the top piece ash. At a very rough estimate I reckon I need something like about 8 - 9% overall, but going on how the timber is working I think I'd need to get perhaps 10-12% from the ash and perhaps 4-5% from the blue gum.

Rob, I don't really need to do any more drying tests, I saw how it dried out when it came out of the water and tracked the timeframe while I was going back and forward to Darwin so I hope to keep this moist right through until launch once I've dealt with it after this soaking so that I don't have to worry about it again.

[skaraborgcraft]

interesting reading. My oak koster can take up to 2 months to swell after 8 months ashore every year. Last year before winter onset,i sprayed the hull down inside with a cuprinol/linseed mix, and then an anti freeze spraydown before the temperture went below zero. She has remained tighter this spring than previously. It could definately take some months to swell,but as already quoted,wether she takes up fully is another thing. I find hard cooking fat/lard is a great filler for any open seams before launching,just dont let the boat stand in the sun too long after though.....
Will be watching with interest. Cheers

[RFNK]

Gyro lives!

This is great!
Rick

[skuthorp]

Check your PM's Rick

On the subject of linseed, when I owned a wooden spoked wheeled vintage car I had 2 sets of wheels, one of which more or less lived in linseed whilst the others were on the car (an old Dodge).