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Maurys

Centerboard Schooner C. Chase 1846 by Maurys - Scale 1:48

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The Centerboard fishing schooner C. Chase was built about 1846 by Willliam Skinner & Sons for Wellfleet, Mass. owners.  From the National Watercraft Collection by Howard Chapelle:

"It represents a type much favored in the Chesapeake oyster fishery...Some were shoal-draft keel vessels of the pungy type, others were centerboarders like the C. Chase, but all had sharp lines and were designed for speed...Their centerboards, and the mast as well, were usually of the centerline of the hull to bring the board far enough aft to give the proper balance to the rig used.  They carried large sail areas and lofty masts.  At about the time this schooner was built, the longhead began to replace the "naval head" in the Chesapeake."  If anyone an explain the longhead vs the "Naval head", I'd appreciate it.

The lines were taken from a Builders Half-Model in the U.S. National Museum [USNM 76098] and presented in the book and offered by the  Smithsonian.

Length between perpendiculars:  60 '- 7"

Moulded beam:  19' - 2"

Depth of hold:  5'

If anyone has more information about the size of the "lofty masts", please let me know.  I have recently seen an old photo of a similar boat with REALLY tall masts.

 

C.Chase1846.thumb.jpg.02d493a2eb730d2497fb6a9c43a14351.jpg

Maury

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Hello Maury

those lines do look quick, the run aft underwater is very clean. Was the need for speed something to do with the economics of the oyster trade?

 

Is there any similarity with Slocum's Spray? (albeit longer & larger....)

 

Mark

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Mark,  In that era, I think speed was becoming much more important in getting fresh goods to market.  Look at Chapelle's
"Search for Speed Under Sail".  See Ed Tosti's Young America log.  Those boats were built with little regard for capacity. 

After building the Anchor Hoy with it's bulbous bow, I'm really looking forward to doing this.

I think Spray was a smaller sloop albeit involved in the oyster trade.

Maury

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I'm lofting (using TurboCad 2018) a new set of plans based on Chapelle's drawings.  It's a long process and several episodes of throwing away work because I did something wrong.   I've made a contact at the Wellfleet Historical Society  who said he would look into any info. he could find on the boat.  Randy Biddle has been quite helpful in  finding obscure drawings, construction methods, etc.   Nothing special to show with a picture yet.

Maury

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Earlier in the year, when I visited the Chesapeake Bay Maritime Museum, I purchased a copy of Chesapeake Bay Schooners by Quentin Snediker and Ann Jensen.  It contains lots of historical information about these schooners, many pictures, and a handful of plans.  It may be useful for this project of yours.

 

I think "longhead" refers to how, at the bow of Chesapeake schooners, pungies, bugeyes, and skipjacks, the stem extends forward and narrows to a sharp point, with traditional painted trailboards integrated on either side.

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While lofting (and re-lofting) I've run into a few questions.  Latest ones regard the framing of the transom area.  Randy Biddle (Windship Studios) has provided me with a lot of photos and drawings from the region that are proving quite helpful.  Three of the many are shown below.

Ship6mod.thumb.jpg.4e240d2c9efe4289bcaf6200049c14fd.jpg

 

 

Ship8mod.thumb.jpg.f3e834effeb468f84bf7e969f299d208.jpg

 

 

Ship11mod.jpg.f97a9d62addcfbb7afbe5603f8f6b80d.jpg

 

Back to lofting.

Maury

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Posted (edited)

Taking a break from lofting in TurboCAD, I will start with the keel components.  First done was the rising wood.

CC_rising-wood.thumb.jpg.0f4d1594bfc44a69d86ea8195103a95f.jpg

The rising wood is 4" x 10", the notches are 2" deep and 8" wide after cutting out 1" on each side.  All work done on the Byrnes table saw with a sled.  The piece tends to bend with so much meat cut out so it's being held to a piece of 1/4" slab until it's glued in place.

Maury

Edited by Maurys

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More work on the keel.  The rabbet measures about 2 1/2" wide.  I started with a line and a scalpel and gave up after about an hour..  Back to the table saw and a .032 slitting blade set at about 1/32" deep.  I started aft of the section where the keel starts to rise (about an inch aft of the end) and ended where the stern post intersects.  The cut was brought to a sharp edge at the top of the keel with Swiss files.  The section of the keel where it rises from 9" to 10 1/2" was cut and filed by hand.  The lower edge of the cut will be most visible and I wanted it as perfect as I could get it.  Enough for today. 

CC_Keel2.jpg.3177205071dce520a015606418c9075f.jpg

Maury

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I cut the sternpost.  93 degrees on the aft side, fore is 98.5 degrees.  The tenon will fit into the keel but I don't have access to my mill for a while so I'll do the mortise later.

CC_Sternpost1.jpg.8754dbd1f9d91664d33f5143e46ed301.jpg

Maury

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Stem wood in progress.  The pieces are propped up with some scrap and the joints are tighter than they appear.  The 4-40 brass bolts

I was going to use to hold the keel down to the building board are too large (diameter) to safely go through the keel so I've ordered some 2-56

threaded rod with a .086" diameter.  A 3/32" hole will leave enough meat on the keel which is 8" (.1668" at scale).

CC_Stem-wood1.jpg.493ea4a7b1d74ff41b98bf68c6fb8a97.jpg

The steps for the cant frames are 1/32" patterned wood added to the stem stock.  It's easier for me than to uniformly chisel out the steps.  Now that those thicknesses are established, I'm going back to re-loft the cant frames.  I had originally drawn them butting up against an 8" stem but the new stem means I have to add 1-1/2' (1/32") to the frames.

Maury

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Good start Maury - I'm signing up to follow along.  Your C. Chase build is very similar to what I'll be doing on the J T Leonard after my current build of the skipjack Kathryn is finished.

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I received the 2-56 threaded rod and nuts.  The nuts are buried in the rising wood and cemented with epxoy.  There are two retaining bolts, each far enough away from the centerboard location so that the mounts will not interfere view of  the partially dropped centerboard.

CC_Nut-Imbedded-in-keel.thumb.jpg.44ad8ce56078610d011de05bc900456a.jpg

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Posted (edited)

This is my first attempt with cant frames.  Lofting them was only a minor challenge  but could not have been accomplished without Wayne Kempson's "Drafting Ship Plans in CAD" posted on this site. 

I pasted the patterns on 1/8" (6" at 1:48 scale)  box wood, cut them to the outside lines and trimmed them back for the bevels.  The first set of cants lie at 70 degrees  so careful sanding was required for a good seat.  Holding them in place while glue sets is another challenge.  I assembled a jig using one of my small machinist squares and a piece of clear acrylic.

CC_CantJig2.jpg.8d65c8142c9026ddf10e0f7feebfb315.jpg

This allows me to keep the frame plumb at the same time as it is lined up on the building board.

CC_CantJig1.jpg.752d3d60f7a63ec59bacf1f684179d6b.jpg

The frame piece is clamped to the acrylic plate and everything is lined up with the plan on the board.  (The front braces for the stem had to be removed to allow room to maneuver.).

End result of the first set shown below.

CC_CantFrameL1.jpg.8c4b54e6cb371f0dc129bf7cbc19959c.jpg

CC_CantFrameL2.jpg.5818776ee72c3c78ae73097514d497de.jpg

 

They were allowed to dry over night before removing the jig.  The next set will be done in a similar manner.  I think some scrap spacers need to be applied at the tops between the frames.

Maury

 

Edited by Maurys

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All 4 cant frames are installed.  By the time I get the spacers put in, I think it will be quite stable.

CC_CantFrames-Fore.jpg.f0c6ca3a6f616378814fe201071fc8fe.jpg

 

I built up the first square frame (H) to check on fit, process, etc. Aligning the fit over the rising wood is critical.  A jig was built...just cutting the slots in a dummy piece of rising wood to accept the frame pair.  The frame pairs are glued together and held with clamps (more clamps than shown in pic.) while the glue dries.  I will bevel the frames while paired but before installation since the floor and futtock pieces are fragile.

CC_CantFrJig.jpg.3b367b2312fad7504389d64d445430d3.jpg

CC_CantFrJig2.jpg.df0ebe4e7b4dbcba8e8f9b57a08d880a.jpg

Maury

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Installation of square frames:  This (Fr. H)  will be the only square frame I install at this stage so I can fair the inner faces of the cant frames.  The process is precise and relatively simple given the building board and its accessories.  The building board had the full-breadth plan pasted-on.  There are two Building board square frames [BBSQFR].  Their faces are square to the board.  The BBSQFR faces are lined up with the aft lines of the frame on the plan using a machinist square. 

CC_FrameInstall1.jpg.9163932fca5951e27b835d0e58f21596.jpg

CC_FrameInstall2.jpg.2e52596d6fd4179f167b6c39d066c6f5.jpg

 

 

A long 1/8" (thickness of the frame half) beam is set on top of the futtocks #3. The tops of Fut. #3 were cut precisely to length and the top timbers  were cut proud. Since the beam is the same thickness as the frame, the face of the beam, clamped to the face of the BBSQFR aligns the aft edge of the frame pair with the plan on the board.  Holding the Micro Mark digital level on top of the beam, I can make sure the frame is level side-to-side.  The beam is clamped to the BBSQFR  and the timber tops are clamped to the face of the beam.  Ready for glue.

Maury

 

 

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Nice work.

 

How do you plan to handle the centerboard?  It looks like it slides down to one side of the keel.  Will you plank the hull first, then cut a hole for the centerboard?  Or do you create the hole now and add the frames around it?

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Peter, The Centerboard setup was one of the reasons I chose the boat.  The well is integral to the design of the boat.  The keelsons are built up in the area as can be seen on the drawing below.

CC_CenterboardWell.jpg.b0b61dbaf49b22f522e698fdf1fb270b.jpg

This is a cross section of the Smith K. Martin from the HAMMS Collection at the Smithsonian.  It shows the details as well as anything else I've found.  The frames attach to the bottom plank of the well and not the keel, so everything is tied together.  I plan on leaving several well planks off to show off the centerboard and its operation.

Maury

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In the case shown above, it's an off-centerboard! Usually the keel widens and the board passes through it centrally.

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And to add to Druxey's comment, while the centerboard is off-set (to port), the main mast is set off-center (to starboard) to counter the effects on the ship's handling.  While the setup is unusual, it is not unique.

Maury

 

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On 7/28/2018 at 1:35 PM, Maurys said:

I plan on leaving several well planks off to show off the centerboard and its operation.

Neat.  I look forward to seeing that.

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I happened across mention of the offset centerboard in my reading last night. The author stated that the mainmast and step were offset to the opposite side to balance things up, or the boat would be better on one tack than the other.

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Druxey,  Thanks for your comments. It's odd to see a mast off-set, but it seemed to work for them.  Most of the other centerboarders I looked at before deciding on this one had the board going through the center of the keel, requiring beefing up the keel along the mid-section.  I'm not sure that having 9 frames end on the CB well structure would be all that strong, but take a look at the keelsons  in the drawing I posted a few days ago.  A lot of meat there.

 

Maury

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