Sistering or repairing ribs in a wooden lapstrake.

I need some suggestions on what to do about several broken ribs in my 1963 White wooden lapstrake boat.I can elaborate more if someone can help me with this. Look forward to hearing from you.

 

Sistering or repairing ribs in a wooden lapstrake

Jeff. First - how many is several ?
By 'sistering' I assume you mean inserting a new rib beside the broken rib.
We called it 'twinning' - same thing of course. Just semantics.
But a whole row of 'twins' looks pretty tacky so it's best to replace the damaged pieces one by one (not in one 'fell swoop' - or you may lose the initial shape).
Steaming ribs is not 'rocket science'. Try to match the original timber: oak, hornbeam, ash or larch, whatever. Measure original diametres of rib - and cut the lengths up to at least a foot (12 inches or 30 cm) proud.
Rig up a steam box. A length of drain pipe (again two to three feet longer than the rib timber). Prop it securely at a 45 degree angle. Block the bottom end apart from an aperture to take a piece of garden hose - which is in turn attached to the spout of an 'old fashioned' kettle. Fill kettle with water and boil on a camping gas stove (or even open fire). Keep the kettle filled and steam the timber for at least a couple of hours.
Meanwhile make a cardboard/ply template of the rib curve. Place it on a piece of scrap timber board (at least six inches thick to prevent warping under pressure) and draw the outline. Then put raised pegs - or strong nails along the outline at 3-4 inch intervals. This is your 'form'.
When throughly steamed remove the 'rib' from the 'box' - and use gloves because it will be hot. Then ease it into your 'form'. Leave it to cool.
When you remove it - don't worry if it loses a little of its curve - it will still be workable. Remove the old rib, and ease your new strip into place and 'rivet' home. Trim off any surplus. Give it a good lick of linseed oil.
Alternatively you can 'laminate' a new rib in place (or use the cracked rib as a template) Thin strip glued upon thin strip (even marine ply strips serve well). However you end up with a 'rigid' rib which won't 'breath' with the hull - and may be prone to further cracking.
Steaming from scratch is best - and not half as hard as describing the process.
Good luck

 

This is a 1963 WHITE 20' wooden lapstrake I am looking for folks input on how I should aproach this repair.I would like to do it myself depending on what it entails.If I am in over my head after getting all the info I need to make the decision weather to attempt to do this job myself or start saving my pennies to have someone else do it.Hears the story.I noticed the boat was leaking pretty good. I removed the flooring to find eight ribs broken on the port side of the boat right where the bend in the rib is the strongest.These ribs are about mid ship.The ribs are about an inch wide and five eights thick running from under the gunwale to the otherside of the hull.These ribs are about six inches apart from each other and go under the floor supports.The questions I have are as follows.Would I need to steam these new ribs to install them.Should I take the floor framework up to replace these ribs or do I work around the floor frames?As I said the only hard bend in these ribs is at the point just where it passes under the floor frame and heads towards the center of the boat.It woul be a big job to take all the floor frame work up.My concern with steaming and useing a form is that most of the rib is pretty straight except for the sharp bend where the side of the boat meets the bottom.I wonder if i should staem and quickly force the rib into place and skip the form.I invision running sisters right between the old broken ribs.Then refastening the new sistered ribs to the strong part of the strake.Don't get me wrong I love this boat and it is still quite pretty to look at but it's not a one of a kind and I would never expect to get out of it what I have into it.So with that in mind I am looking for a way to repair this craft that will be strong but not to concerned about keeping it original.Thanks in advance

 

Sistering or repairing ribs in a wooden lapstrake

Jeff - steam as I described. You'll be surprised just how 'sharp' a bend a well steamed piece of wood can take.
You shuld be able to work behind the floor supports as they shouldn't be in contact with the lapstrake hull planking. Rather they, themselves should be supported on the internal keel timber.

 

Milling the ribs.

Question:Say you have a board the thikness of one and a eigth inches by say six inches.Would it be ok to rip the ribs by taking them from the edge of the board.Say 1 1/8 by 1/2 inch which happens to be the thickness of the ribs needing to be replaced.My guess is it shouldn't matter as long as the grain is followed.The other option would be to rip the board to the 1/2 inch thick and then make your 1 1/8 ribs out of that.I'm just wondering if there is any difference in strength , bending and steaming milling the ribs one way or the other.I hope my description of what I am asking is clear enough.I really want to save this old girl and I'm just trying to get as much info as possible befor I take the mighty jump.I have built small houses and additions on my house but when you get into this intracate kind of work I get a little scared.Look forward to anyones input.Also is white oak the stuff to use these days to make these ribs out of?The original is red oak I beleive. This boat lives in salt water

 

Sistering or repairing ribs in a wooden lapstrake

Jeff - I think I understand your term 'rip', by which you mean cut to shape via a 'jig-saw' from a solid piece of timber ?

Never done this myself. Always 'steamed' - which isn't too difficult.
Cutting to shape from a solid piece will surely at some point cut across the grain - even by a few fibres - and weaken it, leading to splintering.

But there may be old hands out there who know better...
Sorry can't be more decisive.

 

Jeff, I believe we've discussed your boat a few months ago.

The ribs in your boat are vertical grain white oak, not red. Sistering is a valid repair, but I suspect there are more then a handful.

Run you eye over the curve at the turn of the bilge, particularly in the last half of the boat where the curve is quite tight. Sight down each rib and check for fairness of the curve. Any ribs that seem to have a kink or un-smooth transition around this curve, usually means a crack or break is living within. When the ribs were put into the boat, they formed smooth even curves, anything other then this suggests a problem (likely a tension crack or break) which should be addressed.

There is no fast way to install replacement or sister ribs. The stringers and furniture has to come out. It's not as bad as you think, just work slowly (those bronze screws will strip the heads easily) and don't use a power drill and screwdriver bit to remove the screws (you'll just tear them up) Break them loose by hand with a well fitting driver, then back them out. There are less then 100 screws holding the whole of the insides of this boat together and the job can be performed in an afternoon, if you work steady and don't break or strip many.

Replacing ribs on this boat is easy, but does require some experience with bending wood and working with the odd clamping/bracing difficulties, that are typical of repair work. Lapstrake repairs are among the more difficult (some say it is the most troublesome, personally, I think cold molded is more difficult) of the wooden construction methods.

Cutting rib stock to be bent is another difficult issue you need to overcome. Yes, you can rip the edge of a board and use it for rib stock, but it's wise to have the stock over size to start and then dress it as necessary after it's ripped. The problems when doing this are the ripped stock usually follows a fence on the table saw, regardless of the grain. Even straight grained lumber will have run out and this will rear it's ugly head when you bend, with lots of broken attempts. Trust me, in the last year I've bent a little over 100 ribs of differing sizes and you need the stock to be the prettiest stuff, with the straightest grain and it has to be cut correctly or you'll break a lot of frames as you try to install them. What happens is the bend goes great until you try to get it to seat home in the hardest turn of the bilge, where a loud bank will erupt as the frame self destructs. The lumber for this should be green or at least naturally seasoned. Kiln dried lumber will just result in much more breakage (every other one usually).

So to summarize, if you're going to put in sisters you have to remove the stringers and furniture. Since you have to gut the inside of the boat for access, you might as well just replace the afflicted ribs, rather then sister. It's likely the last half of the boat has many cracks and breaks in the ribs, usually found at the turn of the bilge. The rib stock is white oak and should be green or naturally dried. Cut your stock with the grain, not following a fence. The end grain should be vertical or near so and it's orientation should be perpendicular to the planking when bent in place. You are going to need help on this project, preferably someone who has done this type of work before, because building a house isn't even close to the skills necessary to repair classic lapstrake construction.

 

Thier is a good article on selecting and milliing stock for steam bent frames in the current issue of woodenboat magazine, actually it's part of a 8 part series by Mclave Philbrick and Giblin,

 

Yes Par this is the same boat we spoke of.I only threw the house building thing in there so folks would know I've worked wood a little.I am totally aware there is no comparison to house building and fine boat restoration,thats why I'm here asking you.So all the furniture and the floors are out.When you mentiond the stringers have to come out do you mean just the frame work that the floor sits on?Not the big keel timbers that run the lenght of the boat as there seems to be plenty of room to get the new ribs under those.Yes the sharp bend in the mid to stern area is where these ribs all broke.Though I have never done steaming befor I have seen it done along time ago and I would like to try it.I do understand the part about the run out on the grain and I understand what you said about not useing the fence on my saw but i'm not sure if I know wood well enough to look at a piece and follow the run of the grain. Seems like there might be alot of waist that way.Or the other side of the coin is I could waist it on the other end with broken stock. I might be able to get a friend of mine who plays around with building little boats to take a look at my stock befor I try to mill it. But its so hard to track that guy down.I dont understand what you meant when you said ( should be vertical or near so and it's orientation should be perpendicular to the planking when bent in place) Is there any way can you translate that into average joe terms LOL !!So I guess my plan would be to do one rib replacement at a time that way to better insure the shape of the boat.I'm terrified I will get this job going and have changed the shape of the boat. But what have I got to loose.So with the boat on blocks and stands on the side if I take out the floor framing on this boat to do the replacement of the ribs will the boat loose its shape? On the steaming some have suggested putting the rib on a form after steaming to get my bend.Is that correct for this job.I kind of imagined that this stock is small enough that it would come out of the steamer and be fastened as quickly as possible.How long would you steam ribs the size for this boat?Roughly 1 1/18 by 1/2 inch.Assuming I get the correct flow through with the steamer I have planned to build.I understand this repair is going to take some care and alot of time.What do you think a ball park estmate of putting a new bottom in this boat would cost if I had someone who new what they were doing do it.If your not comfortable in saying that I'm ok with that I was just wondering.Haveing a pretty good sence of what I have for a boat, is this boat unique in any way?I have never seen another one just like it, and I live in portland Maine right on Casco bay.I have seen several that are simular but no "Whites".I know I have asked alot of questions but you seem to be a well of knowledge.I really appriciate all your input.Thanks.

 

Hi Jeff, there should be a stringer or two on either side of the centerline of the boat, a stringer at the turn of the bilge, possibly one on the topsides (about half way up it's flanks) a clamp at the sheer (deck line).

If you're good (you're not) you can leave these in place and slide the stock under the stringers as you install them, which helps hold them in place as you brace them down. This is difficult for the backyard type of repair. It requires a number of hands, all knowing what to do and speedy work. The rib needs to be braced in place in just a few minutes, the faster you can do this the less likely you'll break them. You pass a hot rib down through the sheer clamp, bouncing it past each lap (a helper will need to lift the heel clear of the plank laps) under the topside stringer, around the turn of the bilge (under another stringer) then across the bottom, but you're fighting the laps the whole way and it a slower way (time is real important remember) With good coordination, a framing team can slam lots of ribs this way, the sheer clamp helps hold the top of the rib, so you only need to brace the turn of the bilge and bottom. Bracing is done anyway you can. I use scrap sticks braced off of rafters, walls, the opposite sheer clamp, what it takes to get it to sit down were it belongs. A steamed stick of the dimensions you need is very limber and easily worked into a tight spot, but after a few moments, it's a hot, wet, solid piece of lumber again, which will break if you talk to it harshly.

These boats were framed (ribs) upside down over a set of molds. In a carvel hull sliding ribs past the planks is a piece of cake, but in lapstrake it's a pain in the ***. You're better off temporarily bracing the hull, to limit hull distortion, removing the stringers (leave the sheer clamp in place) and doing ribs two at a time (one on each side) This means you'll have more steamer time, but can be compensated (to some degree) when the steamer is loaded with stock, by staggering the stocks introduction to the steamer. Load two sticks, wait 5 minutes, then two more, etc. remove the first two after about an hour, fit it and then grab the next two.

You could make a plywood template of the rib location and bend these girls on a table (a lot easier for the average guy) but this means a template for each rib. When bending on a table (I use blocks of wood screwed down to the shape of the bend) incorporate about 10% more curve into the rib to account for "spring back" when the clamps are released. There are draw backs to every method, this one requires a bunch of templates (don't be tempted to use the same one for similar ribs) which need to be accurately made and don't go into the finial product. This is a better way for amateur's to do it in my opinion.

There are three types of end grain you'll see on lumber, flat grain, quarter sawn and vertical grain. Flat grain is what is typically found at the lumber store, vertical and quarter sawn boards usually need to be ordered or found at a specialty store. On the end of a 2 x 4 the 4" side will have flat grain, that looks like a shallow curve facing or bowing away from that face. Quarter sawn lumber will have the end grain running at a crisp angle (30 to 60 degrees) to the 4" face, which make the lumber much more stable. Vertical grain is similar to quarter sawn, but the grain is near perpendicular to the 4" face and is the most stable cut you can get. Quarter and vertical grain lumber is the prettiest too, used in fine furniture building for centuries. The face and grain pattern on a sheet of regular old plywood is an example of flat grain (though not truly accurate)

The reason you use vertical or quarter sawn stock on frames (ribs) is, flat grain will open up and tear out on the outside of a bend, which is usually the beginning of a break. Vertical grain lumber has a better cellular structure orientation for compressive strength, which the inside of the bend will require. When you cut your stock the end of the rib should look like

[IIIIIIIII] or [/////////] and that's how it goes in the boat, with the grain fighting the bend, not with it.

Other common areas of difficulty in your boat are: the top of the stem (rot) the bottom of the stem, where it meets the keel (rot) The first full size ribs in the bow get rot in the bottom ends, under the transom knees and the transom are prone to rot issues too, the plank to transom fasteners should be checked for looseness. If a lot of debris has been inside the boat (leaves, twigs, etc.) then the gaps under the ribs need to be cleaned out and check for rot. The through bolts in the transom knees need careful bedding and are known to leak and cause rot, check them, especially the ones going through the bottom.