Friday, August 19, 2011

Friday, August 19

Happy birthday Han-Ray! A big one – today he becomes a teenager (sorry Charlie).

OK, the agenda for today is to shape the spars, fit the breasthooks, talk about/demonstrate fitting furniture, and discuss prep work.

The hollow mast was placed on new “v” shaped rests. We then power planed the high corners, which were loaded with epoxy. This is an iterative process of bisecting the angle, rotating the mast, bisecting the angle, until the 8 sided structure now has 16 sides. Switching to hand planes, 16 sides is taken to 32 etc. until definitive facets can no loner be seen. Sanding is done using sanding blocks made of 2” foam insulation. A piece of 36 grit sandpaper is placed on the spar (rough side up) and a block of the foam insulation rubbed on it until it begins to conform to the mast shape. The paper is then reversed and held on the now curved sanding block and sanding begins.  Mast building photolink begins at:  Just hit "older" selection at top to go through the sequence.

The solid spars were marked using a jig. If the opening of the jig is “x”, the space from one side to the pencil is 7/24 x. The distance to the second pencil from the other side of the jig is the same, ie, 7/24 x.
As long as the edges of the jig are on the spar, the ratio remains constant, regardless of the spar diameter. They were then planed to the marks, creating an octagon. The shaping procedure is the same as for the solid spar.

The breasthook teams did a great job. They first made a pattern out of luan. On the pattern, they indicated bevel angle. The rough cut of the blank was done on the bandsaw with the table appropriately angles. Much fitting and shaping ensued. Sorry to be vague, but Brian and I were planing/sanding the main mast.  Here are some breasthook photos.

Geoff demonstrated how to measure and scribe patterns for the boat's furniture. Again, luan patterns and compass scribing. He also demonstrated how to make measurements for correct placement within the hull.  Photos are here.

He then talked about prep work and painting, which takes him approximately one month. High-build primer is applied and sanded and repeated. Paints were discussed. Actually, Rustoleum would be ok, but for the best job, Brightside or Pettit one part polyurethanes should be used. They are rolled on and tipped with a foam brush. Up to five coats, especially for light colors, are needed. Varnishing is no more difficult than painting.  Paint photos.

Our Ness Yawl, with new owner, Ed Storey
Finally, we gave the shop a last cleaning and packed up the Ness Yawl with everything Ed could lay his hands on, including plane shavings for his wife's chickens, or that's what he claimed. Ed then had to frantically look around for a trailer. He eventually found one in Bangor.
Friday night was the lobster cookout, which was nice but foggier than last week's. Han-Ray had a birthday cake and we all sang in a way not soon to be forgotten.

An incredible two weeks. Many thanks to our instructor, Geoff Kerr, for his insightful instruction, his patience, and for never losing his cool (“we can fix it with some epoxy”). We were privileged to be able to work with him. And to my classmates: Thanks for generously sharing your many talents, for your good humor and friendship. You made the two weeks fly by. Keep in touch, and please let me know about your boat building endeavors.

The Ness Yawl Class of 2011

Geoff Kerr, Instructor Extraordinare
Bill Gehring, NY
Charley Jahn, IL
Han-Ray Jahn, IL
Brian Miller, CA
Mark Miller, CA
Ed Storey, boat owner., NH
Aaron Ward, TX
Yenching Wu, CA

Age range of class at start: 12-79!

All photos of the Ness Yawl 2011 class may be viewed at: 

Thursday, August 18, 2011

Thursday, August 18

Epoxying between block (which were installed the previous day)
 We started with the rails, the outwales (gunwales) and associated spacer blocks. During the whole process it's important to keep the parts correctly labeled (e.g. port inwale, arrow toward bow). There were three outwale pieces on each side. The cuts, ie, eventual scarf location should be located so that a) they are in the same location on the port and starboard pieces and b) the inwale and outwale pieces have scarfs at different locations from each other (but same to their corresponding part on the other side.

The bow outwale pieces are fitted first. They require a compound bevel; cut with handsaw, refit, adjust, etc.   See photos here.    Once satisfied, dry clamp the pieces. Repeat with stern pieces. With bow and stern pieces clamped, mark where the scarfs will fall on the spacer blocks, which had been glued in place yesterday.  Dry fitted wales can be seen here.

Note: Our spacer blocks were glued even with the top of the sheer plank. If you prefer, you can glue them slightly proud. Thus the out/inwales must also sit proud. This allows for a narrow wood strip to be fitted to the gap, covering the plywood end grain of the sheer plank.

Scarfs in plywood are generally 8:1; in natural wood they are 10 or 12:1; we used 10:1. Thus the scarf length of a 7/8” outwale is 8 3/4”; so measure out 4 3/8” from center of scarfs. The inwale scarfs are on 5/8” stock, therefore the scarf is 6 1/4”. The scarfs should be drawn so they fall on spacer blocks to facilitate clamping. [Note: Geoff uses a jig for 12:1 scarfs at home]. Sketch in the angle of the scarfs and cut with a bandsaw and finish with a plane. The scarf direction should use the same principle as the plank scarfs. For example, the bow wale section should be undercut so it rides over in undercut scarf at the forward end of the middle piece.

Next Geoff talked about and demonstrated casting lead for the centerboard weight. A propane powered heater (the kind used for deep frying turkeys) is used. The melting point of lead is 621.4 degrees F. A cast iron pot or even a coffee can may be used. There are various sources of lead, including balancing weights from tire dealers. The size of the hole in the CB into which the lead will be poured can be calculated. Since we know the density of lead (0.41 pounds/cubic inch) and the thickness of the CB, and we want a 10# weight, the calculation is straightforward: 10# divided by .41#/cu in = 24.4 cu inches of lead. For purpose of the calculation, I'm assuming (perhaps not correctly) a CB thickness of 3/4”.

Πr² x t = 24.4
r² = 24.4/Π x 0.75
r = 3.22 or approximately 3 1/4” radius.

As the lead is heated, most contaminants float to the surface and can be skimmed off with a slotted spoon. The lead is poured into a leveled CB with a plywood backer board covering the bottom of the hole.  The casting process photographs can be found here.

Next, Ed and I created blanks for the breasthooks (12” and 15” equilateral triangles). The 2+” thicknesses was laminated from plywood. The breasthook is a complex shape. It is roughly triangular in plan view, but the sides curve along the inwale. In cross section, it has angled sides corresponding to the inwale angles, and the top surface is convex and the bottom surface slightly concave.

We then turned to mast/spar building. The main (fore) mast is made of douglas fir, and of hollow construction, as mentioned earlier. Other spars on this boat are solid and made of spruce. 

The mainmast starts off as 8 staves. One stave is precisely cut and serves as the template for the rest of them. Stave width equals 40% of mast diameter at each point. The points are marked on the stave, faired with a batten, and cut freehand on a tablesaw.

Both the hollow mast and solid spars were glued up (epoxy).  Hose clamps held the 8 sided hollow mast together.  It rested in several holders on the bench top.  A drill with socket was used to tighten the clamps.

Asides: the Bevel Boss and 3” bevel gauge that Geoff uses are from Southerland Tools   The 3" bevel Geoff uses is no longer available, but the 2" and 4" are.  The batten we used throughout the process measures 3/8” x 3/4”.

All photos of the Ness Yawl 2011 class may be viewed at: 

Wednesday, August 17, 2011

Wednesday, August 17

 Geoff talked about fairing in the bow stem, aft stem, keelson, planks, etc. The first tool is the 9” grinder fitted with 60 grit paper; it removes material very fast. It is important to keep your feet and the sander moving. Sanders should be started while in contact with the wood, and turned off while in contact with the wood. When you find a bump, Geoff advocated going at it “with gentle love” rather than aggressive spot sanding.

When sanding the planks, it is important not to round over the edges; clean, hard lines need to be maintained. They can be touched up later by hand if needed. Corners are initially cleaned up with shaped scrapers and heat followed by appropriately radiused sticks with sandpaper.

It was emphasized that fairing is not done in one step; it is a reiterative process. Sand, fairing putty, sand, etc.  Fairing photos start here.

We were then introduced to the two main types of fairing compounds. One is phenolic microballoons, which consists of microscopic plastic spheres. It is probably the most useful for home construction. West 407 is an example of this. The other fairing material is Quik Fair (System Three). It is a two part product that is mixed as needed in a 2:1 ratio. Whichever system is used, putty knives apply and smooth it. A flexible yellow spreader was used for larger areas. Asides: Putty knives are cleaned using the heat gun; screw holes should be smoothed from the mid-point out on each side. In filling the scarfs, only the gentlest pressure should be applied.

In fairing around stem, keel, etc., microballoon compound can be applied with a pastry bag.

We then set about fairing the entire hull. Screw holes are packed with fairing compound and then the putty knife is set at the center of the hole and pulled outward; repeat from other side of hole. On scarfs, feel for hollows. Use a wider knife or yellow spreader. Use one gentle swipe; don't keep coming back. You can further correct on subsequent rounds. Around stems, keelson, etc. compound can be applied with the pastry bag and faired with the finger tip.

Geoff then went over locating the pivot points for the CB and CB box. Points are indicated on plans, but location should be played with to get ideal location for function and adequate distance from edge for sufficient strength. Play with the patterns. On the Ness, Geoff felt that some adjustment from the plan location was called for. However, by moving the hole, it was no longer through the CB logs. Therefore, the the hole had to be reinforced from the outside of the CB box. The hole is 7/8” in trunk; CB is over-drilled to 1” diameter and filled with epoxy. The final hole through the epoxy is 1/16” larger than the pivot bolt. The pivot hole has a metal washer and neoprene washer at both ends. The neoprene is against the trunk.  Click here for photos.

In the afternoon, we addressed the outwale and inwale construction. The outwale is rounded over with a 1/2” radius on top, 3/8” on bottom; the inwale has a 1/4” radius on top and bottom; the edges of the inwale on spacer side are left square. The larger radii need to be done with multiple passes of the router.

We fitted the CB box. The slot was too small (on the keelson), so one end of the box was planed and the slot enlarged so there was congruency between box opening and slot. Quite a bit of fussing was needed to get the CB box in to the vertical plane; there are no flat areas to use true it with a square. Ultimately, sighting from bow and stern is critical.
Next, the previously cut rail and spacer blocks were epoxied in place, which required more C clamps then most people own, so at home, this will have to be done in installments.

A decision has to be made prior to epoxying the spacers. We placed them flush with the top of the sheer plank. It might be desirable to mount them (and the inwale and outwale) slightly proud of the sheer and later adding a filler strip to hide the plywood edge of the sheer plank.  Photos of the inwale/outwale/spacer blocks begin here.

On to spar making. Look at the plans and check the scale, which is sometimes different for the spars vs the rest of the boat. We'll make spars solid except for the fore (main) mast, which will be hollow. The thickness of some of the solid spars is such that two pieces of spruce need to be glued up. They pieces should be thicknesses equally (in one of our cases this was two 1 3/16th” pieces).

Solid spars are cut to length and a centerline snapped. Half breadths are marked at stations from data on plans. A batten is used to fair out the profile. A rough cut can be made on the band saw, followed by planing. The blank is then rotated 90 degrees and the process repeated. This yields a blank that is square at all stations. The spar is created by then planing from the 4 sided structure to 8 sided, to 16 sided, to 32 sided. In going from four sided to 8 sided, an shop-built marking gauge was used. From 8 sides up, the planing is just eyeballed.

The hollow mainmast requires a different approach. Eight staves are connected using birdmouth joints on the edge of one plank connecting to the square edge on the next one. The thickness of the staves is 0.2 x max diameter (3” in our case), thus 0.6” or approximately 5/8”. This stays the same regardless of taper. The width of the staves is 40% of the diameter at any given point. This controls the taper of the spar. Only one side of the stave is tapered.  See spar making photos.

This process is fully describe in a Wooden Boat article: Bird's Mouth Hollow Spars by Aime Ontario Fraser, WB Vol. 149 (July/August 1999), pg. 31.

End of the Day Progress

All photos of the Ness Yawl 2011 class may be viewed at: 

Tuesday, August 16, 2011

Tuesday, August 16

Big day. The sheer plank was cleaned up and hung. This is a major day in boat building, since the sheer plank is the last one in our method of construction.  The last plank hung, whichever one it is,  known as the whiskey plank. There was a big two minute ceremony toasting completion of the planking, our good looks, and extraordinary intelligence. Geoff supplied Waterford paper cups and a touch of rum for the toast. He then promptly hid the bottle.  The ceremonial cups photo is here.

Next, Geoff demonstrated the scribing process. A line was scribed 7/8” from the top of the pattern blank; this represented a reference line and the minimum thickness of the skeg. Working at the aft end, he started with the a piece of luan approximately the size (in profile) of the milled lumber that would would eventually become the skeg. After placing it in its correct longitudinal position, he then added a leveling block. Once the pattern blank was level, he went over the scribing process which requires a compass. The point and pencil start at the aft end of the CB slot and are held perpendicular to the hull; as the compass is moved forward with the point tracing the hull, the compass is kept perpendicular to the imagined hull tangent at all points. This means that a natural rotation of the compass occurs.  This photos of this process can be viewed by clicking here.

We then split into teams.  While one group worked on the stern pieces, another group of us set about the final fitting and mounting of the outer bow stem. This has to be smoothly integrated into the forward keel. After some jockeying of the stem, we agreed on its correct position and marked reference marks on it and the hull. It was remove and the excess length was cut away at the band saw. The stem also had to be beveled; the instrument of choice was the jack plane. After beveling, the stem was clamped back on the boat and the angle that needed to be cut to intersect with the forward keelson (which had not yet been fastened down) was determined. The aft end of the forward stem was cut first, and the complementary angle was then cut on the bow end of the smaller forward keel. Its length had been trimmed so it did not extend past the CB slot.  Click here for photos of the fitting/shaping process.

End of the Day Progress

All photos of the Ness Yawl 2011 class may be viewed at: 

Monday, August 15, 2011

Monday, August 15

The start of our last week. Geoff began the day with a few tidbits. He reminded us that the parts we began making (rudder, centerboard, etc.) should be store flat; they will warp despite relative thickness. Scarf cleanup was reviewed: heat gun plus scraper followed by 60 grit sandpaper. Then, talking about planking, Geoff demonstrated that if a batten seemed unfair, you can measure the plank at that point and take the corresponding measurement off the mold.

We created the pattern for plank three, faired it, cut the blanks, measured, and then cut the planks. For seem reason (the hour? Too much coffee?) I cut a less than smooth curve that obliterated the line at several points. Geoff to the rescue. After much eyeballing and measuring, he began correcting the edge with a bench plane (#4?) and at the very end, a block plane. We lost only a 16th of an inch from the design width...within tolerance. The gains were then cut as were the rolling bevels on the two #2 planks. The planks were offered up and some corrections made.

The bevel was wetted out (un-thickened epoxy) to saturate the end grain. This was quickly followed by thickened epoxy. The plank was held in place with clamps and temporary screws. Screws had been placed through the plank on molds 3,4, and 5 in the last fitting and then removed. The holes in the planks and molds could then be used to correctly register the planks. The whole process was repeated for the plank on the other side. In each case, squeeze out epoxy, inside and outside, was cleaned up.

Hahn was sent under the boat to do something besides clean squeeze out. He was given a drill with a ½ inch bit and asked to drill a holes near the ends of the centerboard slot. It was a tough job because the bit was last sharpened by Noah. Still, he succeeded admirably. Geoff then cut the whole slot using a straight router bit with a guide on it that rode on the keelson and cut the plywood to conform.

Next we began the last plank – the sheer plank – which is the one that catches the eye and can make or break the looks of a boat. In order to place the luan on the boat to create a pattern, notches had to be placed on both sides of the stems (saw and chisel) on the 2x4's to allow the pattern to reach down to the shear strake marks on the stems. 

The planking process was the same. I was reminded that after the plank is marked and cut in three pieces, and scarfed, it is aligned with the pattern placed over it. The second plank is placed on top of the glued and scarfed first plank, which serves as its pattern.  When we cut the scarfs this time, several of us used hand planes (I used my jack plane and block plane) and we all felt more comfortable than with the power plane. We had much better control.  The scarfed planks were held in place with strongbacks rather than screws this time. 

Geoff then had us return to working on the parts previously started. One operation involved rounding off the rudder head using a router with a pattern bit: 3/8” radius on the solid part and 1/4” on the sections where there was no middle section. 

Next we (read Geoff) studied the plans and planned how to cut the timbers for the aft end (skeg, etc). He then made up a cut list of oversized lumber for the forward keel, aft keel, etc. We then milled these parts to their rough dimensions. Brian planed the bottom of the boat so planks were no longer protruding and thus created a flat spot for all of the parts were were in the process of making. 

Some rudder theory. The railing edge should have a small flat area and then gently sweep down for about four inches. We placed the rudder in the rudder head and marked how far up this feathering would extend. The feathering was accomplished with the big grinder/sander initially (36 grit) – about half way up to the 4” mark. Then the standard 4” grinder was used with 24 grit on rubber sanding disk (this tool is used often by welders) to sculpt the edge of the rudder.  

End of the Day Progress
All photos of the Ness Yawl 2011 class may be viewed at: 

Friday, August 12, 2011

Friday, August 12

Back to the garboards which require  a rebate to be cut at each end (upper outside edges). This rebate reduces the plank to ½ thickness at the bow and stern; a corresponding rebate is cut on underside of the upper edge of the next plank, so at the stems, there is only one plank thickness, half being contributed by each plank. The rebate width is the same as the plank overlap, that is, 3/4”; it goes 15” back from the stems. The thickness tapers from full dimension at 15” to half thickness at the stem. The work is done with a rabbet plane of sufficient width to cover the 3/4” wide rebate. This is done so only a single plank thickness intersects with the stems and can be faired into them.  Photos of cutting the rebates begin here.

Once the garboard was prepared, we created a pattern for the next plank. Three 8' sections of luan plywood are presented to the hull. The width has to be sufficient to cover the overlap and the mark on the molds indicating the bottom of the next plank. The three sections are maneuvered around to accomplish this on the full length of the boat. The sections were then hot glued, forming a single long pattern with an odd looking shape. The clamped panel was then marked. The garboard line was traced, the station marks for the plank bottom transferred, as was the plank bottom from the stems. The stems were also traced (outside). The #4 face was also indicated. The pattern was removed. The top edge was extended 3/4” to account for the overlap on the garboard plank (this is necessary since we traced the edge of the garboard, and the next plank must overlap by 3/4”. A spiling batten (about 3/4” square and longer than the pattern) is fitted. Nails were placed at the various marks, working from station 4 outward. We then stepped back to see if the curve was “fair”, that is, a graceful curve with no unsightly bulges. Small adjustments were made to the batten placement until the fit was good. It was then traced and the batten removed. Second plank photos can be seen here.

The pattern was then placed on top of a piece of a doubled up 4x8 x3/8” mercanti plywood; we cut both port and starboard planks together, insuring symmetry. . The pattern had to be transferred in three sections to this double piece of plywood. Thought had to be given to most efficiently fit the three sections of the pattern to the single piece of plywood.

One section was traced and a scarfing batten (3” wide strip of luan) was placed perpendicular to the section; this was marked “Under” or “Cut”. As you move from bow to stern, the forward part of the scarf is on top and the aft section underneath. The forward section is marked “Under”, meaning it has to be planed on the bottom, and the corresponding scarf on the next section is marked “Cut” since it will have wood removed to create the 8:1 sloping scarf. The marking of the scarfs was done on each of the three pieces. Each was marked as to which side of the boat it would be placed and an arrow pointing towards the bow was also drawn. Next, a 3/4” line was drawn around each of the sections to allow for some leeway in the final fitting of the plank to the mold. The three sections were then cut using the 6” circular saw. The two layers were separated and layed out. Care has to be taken to mark the parts cut from the bottom layer of plywood, and indicating their proper orientation. The scarf areas are drawn in and Under and Over noted on each scarf. This is a step that an error can easily be made and a scarf cut incorrectly.

Next we took the three pieces representing the plank on one side of the boat. Each piece was place on the workbench with the edge to be scarf aligned with the bench. A combination of power planers and hand planes were used used to cut the scarfs. Brian cut a very nice scarf using only his hand plane. The plank is then offered up to the boat. The spiling process was then repeated, again transferring marks from the stems, including their outline (lower edge), plank marks on the molds, station #4 and the edge of the garboard.

We then removed the plank a faired it using the batten. Again, the 3/4” overlap on the upper edge of the plank (note: upper refers to the orientation as we're looking at the boat, which is upside down, so the “upper” edge eventually becomes the bottom edge when the boat is righted). The rebate is created on the inner, upper edge of the plank ends so it will fit into the rebate cut earlier on the garboard plank.

The bevelled edge of the garboard is wetted with un-thickened epoxy. Then thickened epoxy is applied along the edges. The plank is then positioned (from #4 outward), and clamped and screwed where necessary (temporary screws).  The process is then repeated with the blanks for the other side of the boat. The rebates on the lower outside edge of the planks are cut after it is on the boat.

Using the same process, we created blanks for the third planks. The only difference was that when we scarfed them, instead of screwing them to the bench (with plastic protective sheets), we used a 2x3 piece of stock across the joint and clamped to both sides of the work bench.

We finished the first week by assembling starting assembly of the rudder, centerboard, centerboard box etc. as shown here.

End of Day, and Week Progress!
Week one was informative and fun. We have a great instructor and a diverse team with good chemistry.

All photos of the Ness Yawl 2011 class may be viewed at: 

Thursday, August 11, 2011

Thursday, August 11

We began by fitting the garboards, one at a time, to the molds. The plank is clamped  to the center station (mold #4) at one point and adjusted for the best fit, moving the it fore and aft, tilting it, or moving the entire board up and down. Once the fit is satisfactory, the garboard is clamped, moving outward from #4. We made sure there was sufficient overhang on each end.

The plank is then re-spiled.  Lines are traced from the stems to the garboard. Pencil marks are made at each station indicating the correct plank edge from the marks on the molds.

The centerboard slot was also drawn in. The garboard was removed to the bench and re-faired using battens. The process was repeated with the other garboard. At this time, the squeeze-out epoxy from the scarf joints on the garboards was also largely removed using a heat gun and scraper.

Thickened epoxy was then made and applied to the keelson, floor timbers, and stems wherever the garboard would land. The garboard was again fitted in place from the center out. Using #10 bronze wood screws, the plank was fastened to the floor timbers, keelson, and stems. 1” screws were appropriate for the keelson; 1 ¼” for the timbers. Temporary screws were used at the ends of the garboard to fasten them to the stems. The permanent screws were all pre-drilled and countersunk. The keelson screws have to be placed closer to the outer edges since the center area will be planed.  The photographs of this process can be found here.  The process was repeated for the second garboard. It overlapped the centerline too much, that is, interfered with the other garboard. Geoff made adjustments in situ with a hand plane.

Next we began fabricating components such as the centerboard, the centerboard box, and the rudder. These parts are clearly marked on Oughtred's plans. Brian Miller and I worked on the centerboard box. We cut the sides from plywood and then milled douglas fir to the specified dimensions for the rails (the fore and aft support at the top) and the logs (fore and aft support at the bottom of the box. They were left overly long and will be fitted later.

The rudder was built up to specified thickness by gluing 3/8” and 1/2” plywood together. Many glued-up components were gravity clamped, that is, heavy objects such as batteries, were placed on them.  See two photo sequence here.

From here on, any planks glued in place had to have excess epoxy scraped from the underside of the hull. This task fell to our youngest (12, soon to be 13), and smallest classmate, Han-Ray Jahn. He does an excellent job.

Then it was back to planking. We bevelled the garboard (see photo). This is a rolling bevel. To guide the planing, saw kerfs (photo here) were made at each station by holding the saw parallel to the mold section corresponding to the next plank and then sawn until it touched a 3/4” line scribed earlier (this is where the next plank will overlap the garboard.

End of Day Progress

All photos of the Ness Yawl 2011 class may be viewed at: