Ribbands and Backbone

Part of the setup for a carvel constructed boat, ribbands, are fore-and-aft stringers (explain one piece of jargon with another) that the boat is built over. They are used (for Seapod) to define the shape that the timbers are steamed over and to which the planks are then attached (attached to the timbers that is). After some trials to establish how thick and wide the ribbands need to be it amounts to a couple of days work. Each ribband gets notched into each mold and is then screwed in place (with a lot of twist applied where necessary).

Rob is working with me on this stage of the project and we soon get into a rythmn where we can get a couple of ribbands on in a hour or so.

The last couple of ‘hog’ ribbands get left loose at the ends until we can line up the stem entry in a week or so.

We are using tulipwood for the ribbands (a variety of poplar) which is straight grained and just right for the job. Dimensioned at 31 x 15 mm they are quite stiff and need, once we reach the turn of the bilge, to take considerable edge set and twist. Once complete we realise that the strain placed on the endmost molds is pulling them apart! This is soon rectified with clamps and epoxy dribbled inside the joints of affected molds.

The backbone for Seapod is being laminated in Iroko and consists of two aprons (fore and aft), two stems (fore and aft) a hog and a two slice keel (so that it can be bent and laminated rather than shaped to size). I have decided to use Resorcinol (Cascophen) for laminating and scarfing the backbone - but get the quantities woefully wrong on the first guess (surely a 500g mini pack will be enough) and only get enough to laminate one apron (2.5 sq m of surface)  this week. A second order for Cascophen (3kg) arrives on Friday afternoon and allows us to laminate up the second apron this afternoon (Saturday). This will now, I hope, allow us to complete the rest of the backbone assembly next week - and leave some Cascophen over for key structural elements at later stages of construction. Here is the first apron on the jig.

Once the aprons are cleaned up we will cover them in parcel tape, place them over the former and use them as the template over which the stems will be laminated.

The Iroko is hard to work - but rewarding. The prickly grain needs very sharp tools (I have given up freehand honing and succumbed to the temptation of a Veritas honing system - so getting sharp blades is now easy - but cumbersome). Lots of the planing gets done diagonally or even across the grain when things get tough. In addition I have to (i.e. choose to) wear a full dust filter system while working the Iroko - I’d hate to do this in a hot climate. Anyway - I’m happy with the choice of backbone timber - fairly light - SG is 0.62 or so, a tough and stiff glue system (Resorcinol) to hold it together and in place. I wish I could find a way of making it stay the beautiful yellow that it has when first worked - rather than ripening into the common or garden mahogany-like red. Here are the two keel laminates just after they are planed down to size.

Mike and I work all day Saturday. Rob comes in to help with our lamination and Polly and Merry both do some work on their respective boats. The weather in Lyme is wonderful (for January) and Mike and I open the big front doors. Tourists and locals look in, admire the Pilot Gig and ask questions about the other boats just starting construction. Mike spends the day doing some more wonderful joinery. He tells me that it is related to his sternpost/deadwood assembly but I suspect that he is preparing an entry for an abstract japanese joinery competition. I’m sure that a beer lugger has never been built in quite this way before.

And to show the scale - see the (very large) hands for comparison.

My own joinery efforts to date have been restricted to the more manageable scale of a decorative sliding dovetail puzzle to celebrate Mary’s birthday. Here’s the Iroko bit (I think that I have already said that I like Iroko)

And here is the Iroko/Sapele assembly once it starts sliding together.

I brought a good book today. The ‘Stair Builders Guide’ by Morris Williams (published in  1914). The discipline looks nearly as much fun a boatbuilding.