All posts by Doug

Gunning dory rig up

Marblehead Gunning Dory

This boat was built new in the fall of 2016 to designs found in John Gardner’s Dory Book. I used the lines of Gerald Smith’s 17′ version he adapted from the original Chamberlin molds that he had acquired. Working with the owner I developed a mix of details from a number of dorys to make sure he had exactly what he wanted. We also added an adapted version of the Beachcomber dory rig John Gardner presents in the 19′ Marblehead Gunning Dory. The hull is planked in cedar, the stem,  sawn and bent frames, and inwale and sheer cap are of oak. Copper rivets and bronze screws. The rig is solid sitka spruce.

Below is a brief description of our dory building process for this boat.

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Bottom board assembly

First, here is the bottom board made up with each station’s frame fastened on along with bow and stern stems and bottom board cleats. I Then flipped this assembly over onto a sturdy building jig which allows me to both plank more comfortably and hold the boat to shape while I bend on the planks. 

Here is the boat right after being flipped off of the planking jig. I leave the frames extra long to make sure that the boat holds it correct width at the stations and each cross brace is made specially so that the bottom board has the right amount of camber in it.

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Flipped

Lucky to get some VERY clear cedar from Florida for this boat. This photo is taken while the seams are riveted tight to keep the hull water tight.

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riveting

Once riveted I moved on to seat risers and thwarts. These enabled me to remove the cross braces and install the inwale to stiffen up the sheer plank.

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Inwale install

Once the inwale was installed I removed the thwarts and seat risers again to install steam bent frames between the sawn frames and the centerboard trunk.

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Centerboard trunk install

The hull is coated in Linseed oil based Varnish and paint allowing good protection while moving with the seasonal dry/swell cycles. Here the centerboat trunk cap is being fit with the bronze rod centerboard lifing bar.

 

 

 

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Centerboard trunk cap

The spars are made of 2 face glued pieces of sitka spruce. By inverting two pieces of the same board you can achieve a much more stable spar as the tensions in the wood can counter-act each other through the seasons.  Here I am cutting down the squared adn tapered stock to 8 even sides, before 16 and then 32 sides before being sanded to a smooth round.

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Rounding the mast
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Mast alignment

Now with the hull coated, the rig finished and varnished final rig details are completed. Mast partner knees, boom jaws, leathers on all chafe points. removable sole boards, stem fittings for the jib, oar lock sockets, etc.

The beachcomber rig has a great look! I can’t wait to see how she rows and sails.

Gunning dory rig up
Rig side view.
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Woodwind Restoration

Woodwind came to the shop with a recent survey mentioning a few concerns including open plank seams, loose fasteners adn some separation of repairs in the rig. While she was still being actively said in the summers the owner brought her in this past winter to get these issues addressed.

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Woodwind on arrival was showing her topsides plank seams and her seams below the waterline were dry and open after a winter out of the water.

The garboards were removed to gain access to the bottoms of the frame ends and their fasteners. Once they were off the floor timbers were more decayed than originally thought. The decision was made to replace the worst of them during  the reframing process.

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Once the garboards were removed the floor timbers showed more decay than they initially revealed.

The frames were bent in from the bottom to enable leaving most of the deck structure in place.

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While the initially we hoped to just replace half the frames it was found that almost none of the frames aft of the forward bulkhead could hold fasteners.

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The  remaining plank fastenings were replaced and then the hull was refaired. All the finishes were then restored for a cosmetic overhaul.

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Say When II bottom replacement

When Say When II came to me she had been in storage for about ten years awaiting restoration. There were a number of problems in the bottom that needed attention. In the end we decided to replace all the timber below the chines. Previous restoration attempts had introduced a lot of mixed metals and insufficent wood sealants. WIth various rot throughout her bottom and  considering  her being over 70 years old it was decided everything below the chines would be replaced. We decided the bottom would be double planked with the inner layer laid diagonally and the outter longitudinally like the original, however the layers would be bonded together using modern marine adhesive.

 

Once The interior was removed, molds were built at each frame to help maintain the shape while the different timbers are replaced.

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A small flipping frame was built as we didnt’ have any overhead lifting gear.

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The keel showing decay from plain steel bolts mixed with a bronze prop strut and prop shaft.

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Decay along the keel on the old frames

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The planks still had the original canvas gasket between the plank layers, but the bedding compound had long since washed out. Various areas had different solutions to the water seeping through. Some areas had cotton driven in, and others had marine adhesives pushed into the seam.

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The replacement frame parts,

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Replacement keel laminated out of Mahogany.

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Here the old keel is being used to double check the frame spacing on the new keel for the new floor timbers

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Dry fit on the boat.

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New Keel and frames installed

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Diagonal planking

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Dry fitting the outer longitudinal planking

 

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The two layers were then bedded together with a rubber gasketing layer of 3M 5200. Once cured the planks were faired smooth

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Prime coat

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Prepared to flip back over

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The flipping jig worked great, and enabled the boat to be turned over single handed. The heavy deck ballanced well against the bottom so there wasn’t much of a tipping point where it wanted to move on it’s own or out of control like most hulls.

 

Here the inside of the bottom is ready to be cleaned, primed and then to have the engine and interior reinstalled.

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Framing and floor timbers

This is the first boat I have framed outside in tempatures around zero. I was nervous about the frames being able to retain their heat from the steam box long enough for me to be able to bend them around the mold and get them secured. Because of this concern I gave them all a coat of paint prior to steaming, which helps retain more moisture/heat. The paint sealant and the great framing stock worked great together. They look a bit funny with the steamed paint which will need to be scraped before they get their next coat of paint,  but I only broke a couple frames in the transom where there is a significant recurve and twist.

Once framed I set to making and installing floor timbers. I used a sheet of plastic Mylar to trace a  template off the lofting reduced by only the planking thickness this time, and compared it to the molds. Once satisfied with the fit I took bevels on the hull and transferred them all to the oak. .

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The first few frames bent in place
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With temps around zero I built a quick ultra insulated steam box, but still the condesed steam dripping out would develop icicles.
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The shapes gets trickier in the transom where the recurve pulls up towards the transom and gets tighter and tighter. I had a couple failures, but they mostly went on fairly easy.
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Aft end framed. Once the centerline is notched for the keel the shape in the center fills out to a wide deadwood like skeg. More on that in future posts.
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A canoe like shape forward is starting to develop.
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Floor timbers are beveled, notched for the keel structure and drilled for the keel bolts before instalation. Here you can really see the funny color of the steamed paint next to the fresh oak of the floors.
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Making frame molds & setting up the plug.

 

Once the lofting was finished and pulled up from the floor I set to building a bending mold for each frame of the hull. These Molds when fastened to the floor will serve as a building plug. As we have gone to such lengths to build a classic Herreshoff design I thought it most appropriate to build it in the Herreshoff method.  This involves making a mold for each frame station. it can be time consuming, it allows you  to retain as much of those nice lines from the lofting as possible and thus minimizes time spent fairing wood later. Also since the molds are symetrical around the centerline a lot of time can be saved by building each mold doubled up in half.  A slight complication is that these molds will have the frames steam bent over them and then those frames will be planked on top of that. The boat was lofted to the outter face of the planks, so I need to make a reduction from the outter surface to the inside of the frame. Where the boat doesn’t have much shape this is easy, but where the boat has more shape this reduction can get more complicated since it’s being reduced by so much.  Again, a little more time spent on these stages (no actual boat parts have been built at this point) will really pay off throughout the rest of the build.

Once i had fabricated the mold I took a series of bevels from the station view of the lofting which enabled me to do a rough beveling before setting up the frames. Given a very cold winter it was nice to be able to do as much work as possible in teh shop before taking the parts outside. The frames are all set on stations perpendicular to the hull’s centerline, With the nice lofting floor already set up and leveled I am able to set each station up plumb and then structure them all against eachother and against the floor.

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Measuring out the reductions on a a half mold.
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Squaring the doubled over mold to be symetric and fair
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The forward half of the molds, unfolded and reinforced carful of the total width and the centerline
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The aft half of the molds
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The molds, roughly beveled and set up on their stations. The keel area will later be notched to fit the keel assembly.
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After the first major snow of the winter. The stations are all squared and blocked to eachother.
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Lofting An 1882 Steam Launch

Lofting a new build project is a very exciting process. Especially after about a year of development and preparation this was the point where the project finally felt like it was mine. I always enjoy lofting because, for me, this is when I really get a feel for what the boat is going to look like.

Building a boat to a design of this era poses some unique difficulties.  On one hand the MIT Hart Collection has the table of offsets and a drafting of the original boat. Those combined with Zurn Yacht Design’s scaled computer model  gave me a great starting point for the hull shape, but how the boat is going to be built and held together is left mostly untold. The Herreshoff plans offer some details but left out are a lot of construction details about how it’s all held together in a lot of tricky areas. This is often left to the builder.

 

My first step was to draw the shape of the hull full size on a lofting floor. This is done in 3 different views. One is from the front on, one is from the side and one is looking down. Each drawing thus has two dimensions sharing one dimension with each of the others. The boat’s shape is then given as a series of points along a grid set up in all of these drawings. I could go on at great length about the importance of accurate, consistent measuring, or error due to width of pencil lines or simply how much your knees hurt after crawling around on the floor for a few days, but instead I have the below video showing some of the process.

 

(a short stop motion of the lofting process sorry about the bad lighting, I have since adjusted the camera and have been able to get a better video for the rest of the build)

With the shape of the hull drawn out full size I started to develop how I am going to build it.  Since this is such a historical boat, the goal is to build it as consistent with the original as possible. Here the difficulty arrises.

HMCo was lucky and ultimately as successful as it was because they had a genius designer in-house.  The design was conceived in one building and then built and launched across the street. They also had the benefit of hundreds of years of cumulative boatbuilding knowledge on the floor.  It is said that Nat Herreshoff would make daily visits to the yard and he would often make adjustments to a design long after construction had started and all drafting had been completed. There is little record of any of these later tweaks and changes made on the drafting. Pulling lines off of a well-preserved boat might have provided some insight. However,  since neither  the original boat nor any like it exists today, a lot of problem solving still exists. As tedious as this process may be, I really enjoy the challenge.

The first step in filling in the gaps was to go back to the MIT Hart collection and get as much information as I could about the original boat.  Herreshoff built many steam launches  in the 1800’s, and early 1900’s and I was able to get copies of plans for several similar launches which included different views or details which showed a few more details about how different areas may have been built.

a printed scan of the original plans at MIT's Hart museum
a printed scan of the original plans at MIT’s Hart museum

 

Next I took these plans to the lofting floor and started drawing in various parts of the boat. Some are straight forward. For example, the keel has a precise width and thickness that starts and ends at specific points as shown on the plans. Other parts however needed a lot more investigation.

An example of a very tricky area to figure out was where the propeller shaft goes through the counter timber assembly at the back of the boat. There is a lot going on in this area, there is a large hole drilled through hull well below the water line with a lot of force applied by the rudder, and the propeller.  With all this it is prone to rot and it needs to be built especially strong. The plans show a very simple representation of the area. Once drawn on the lofting floor it seems that there wasn’t nearly enough space to fit all of the necessary parts into such a small space and have it hold together.

This is a picture of the drafting of the stern. showing all the info I have to work from on the original
This is a picture of the drafting of the stern. showing all the info I have to work from on the original

 

Problem solving a trouble prone area like this in an old boat is often a balance between recreating it’s original design and drawing on modern knowledge. With this in mind I approached a few aspects of the area to try and get it right.

The first thing I wanted to change was simply the size of the prop shaft. The original was 1880’s rolled brass and was for a much larger engine, so I could bring it’s diameter down by about a half using silicon bronze appropriately sized for this boat and it’s engine. This was an improvement, but still didn’t leave enough strength for me to feel comfortable.

The next problem was two-fold; I wanted the area to resist rot and be easy to reconstruct if rot were to sneak in over time. As shown in the above pictures there are no details about how this area is held together structurally. So to develop a plan I looked through as many boatbuilding texts as I could get my hands on, I poured through as many images and boat plans old and new as I could and had a conversation with  Walter Ansel who is restoring a similar boat at the Wooden Boat School, and Warren Barker who has been a part of many restorations of  Herreshoff boats. From all of this I decided to make a 2 part shaft log as opposed to the solid one in the plans. This would enable me to bolt together the area in such a way that the shaft log and tube could be more easily replaced without deconstructing the whole boat. I also widened the structural pieces around the shaft. This allows me to move the move the plank ends further forward and up into the boat. Without the planks stealing 3/4″ of width through this area I could make space for the prop shaft, bolts around it, and enough timber to be strong enough to handle the forces generated by the prop and rudder.

This is a picture of the drafting of the stern. showing all the info I have to work from on the original
This is a picture of the drafting of the stern. showing all the info I have to work from on the original

 

my scrap sheet of where the planking, bolts and prop shaft can all fit together.
my scrap sheet of where the planking, bolts and prop shaft can all fit together.
another station further aft showing how narrow the hull gets and how tight it becomes to fit planking, prop shaft and enough structure to hold it all together. see how I have moved the plank ends up out of the wat where there is enough width to get bolts around the stern tube.
another station further aft showing how narrow the hull gets and how tight it becomes to fit planking, prop shaft and enough structure to hold it all together. see how I have moved the plank ends up out of the way where there is enough width to get bolts around the stern tube.
similar counter timber area with rabbet pushed away from the trailing edge leving enough timber around the shaft tube to provide space for timber structure and bolts.
similar counter timber area with rabbet pushed away from the trailing edge leving enough timber around the shaft tube to provide space for timber structure and bolts.

 

after a lot of erasing and redrawing this is what the lofting floor looked like around the counter timber.
after a lot of erasing and redrawing this is what the lofting floor looked like around the counter timber.

Ultimately I doubt that this construction is exactly what  HMCo used, and in that it is probably a deviation from a strict “replica”. However, without an original to build from, this solution best satisfies my  concerns of serviceability and longevity while staying as true to the original as I can.

Some might find that I gave too much detail on that one problem I had to solve, but it’s a nice example of the benefit of lofting and took up a lot of my time in and out of the shop. Had I gone straight into building the backbone I would have had a lot of trouble when I went to plank the hull or drill for the stern tube and realized the boat didn’t have enough structure there to hold together. I have learned that plotting these details out in advance ultimately saves a lot of time and yields a better boat.

 

 

 

History of the design.

I am very excited to be building a steam powered wooden launch from a scaled-down Nat Herreshoff design. Throughout the process, I will be posting here so that those who are interested can keep up to date. To start with I’d like to give some history to the design we choose, and how we went about having the boat scaled down to produce the hull I will be building.

No-94
http://pds.lib.harvard.edu/pds/view/10835441?n=39&imagesize=1200&jp2Res=.25&printThumbnails=no
http://www.machine-history.com/Herreshoff%20Manufacturing%20Company%201800s
http://www.machine-history.com/Herreshoff%20Manufacturing%20Company%201800s

The primary design was boat No 94 from the Herreshoff Manufacturing Company (HMCo.) It was built only once for the United States Fish Commission to be used as a steam cutter for the USS Albatross. The Albatross was built in 1882 and out of the 8 boats that she carried No 94 was one of two steam powered boats built by HMCo. The other one had a very interesting center propeller attached to a universal joint that could be retracted when not in use or when it entered shallow water. Both boats had auxiliary schooner rigs and reportedly moved along nicely under sail alone.

 

Interesting account of Albatross, her construction and the research done on-board.

 

The 26′ No. 94 was built to steam for 3 days and hold 12 passengers when going on marine research voyages from the larger (234’) Albatross. I haven’t yet found out what happened to the original boat but I assume it was lost or broken up, as later photos of the Albatross don’t show this boat. As with all Herreshoff designed boat, the lines are pulled from a half model and then scaled to the desired size.

http://newenglandboating.com/videos/video-how-herreshoff-designed-his-boats.html
http://newenglandboating.com/videos/video-how-herreshoff-designed-his-boats.html

 

 

After Nat Herreshoff carved a half model he would create a table of offsets and then it could be scaled to the appropriate size. The table of offsets for No 94 were  also used for many different boats ranging of 20′ to 50′.  To accomplish the various scales, Herreshoff used a variety of methods. One was to proportionately scale in all dimensions. Another way was to stretch the center section of the boat. The final method was to keep the width and height of each frame the same and adjust the spacing between them.

 

We had a challenge with the scaling on this project. The owner’s vision is to be able to steam around Marblehead Harbor as opposed to 3 straight days in the Arctic and with 4 passengers rather than 12. Most importantly her berth requires a length of no more than 23’. Thus while the owner loved the look of No. 94 he needed to have it made smaller than the original. As we approached the process of scaling down the original design the goal was to keep as much free-board and beam as possible while bringing her down to about 22’ 6”. This would allow for easier handling by the owner while still being seaworthy enough to handle occasional rough water. With these guidelines and the original offsets from HMCo, Doug Zurn of Zurn Yacht Design was able to generate a computer model and scaled down the boat using modern CAD programs. This technology allowed us to achieve the desired size while staying as faithful as possible to the original Herreshoff hull shape.

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While I move forward with building the hull. I will be working with the owner to find an appropriate engine and boiler combination. With this digital model will be able to see the effects that different combinations would have on stability and displacement.