Jump to content

Mediator sloop by bruce d - 1/48 - an 18th century transport scratchbuild from Jeff Staudt plans

Recommended Posts


Mediator was a single masted merchant sloop built in 1741 or 42 on the Virginia shore of the Chesapeake Bay. Purchased for use by the Royal Navy in May 1745 and lost less than three months later, she was caught up in the great affairs of the Jacobite Rebellion. In those three months she was in and out of the Mediterranean; captured by the French privateer La Naiade off the Needles; retaken the following day by HMS Assistance. After repairs she was quickly recommissioned and joined the convoys supplying the English land forces in the War of Austrian Succession. She foundered in Ostend harbour on the 29th of July and was lost just days before the siege of that city began.


61’ 4” length on deck, 44’ length of keel for tonnage; 21’ 2” breadth for tonnage; 9’ 9” draught and 104 74/94 tons bm
Crew: 60 - 80 at different times
Armaments: 10x 4 pounders, 18x 1/2 pounder swivels

Plans of Mediator are in the NMM, id number J0569, see image at beginning of post:


although it would be possible reading the description of the plan to believe that Mediator was built at Portsmouth: she was not, but the plan was and that is what is meant. Chapelle also re-drafted plans for Mediator, see The Search for Speed Under Sail, plates #10 and #11.

IN 2013 Jeff Staudt produced plans for a model of Mediator in collaboration with Winston Scoville. They are downloadable legitimately:


The 1/48 scale plans are in PDF form and print out on seven A1 sheets. They are superbly detailed drawings and apart from a few comments there are no instructions per se. At 1/48th scale the length overall will be 779mm, approximately 30 ¾ inches.

Looking at all the plans together, a couple of points become evident straight away. Mediator was pierced for 14 guns but the stated armament was ten: even that figure may be excessive as it is unlikely the full compliment of arms was carried while in convoy service. The crew figures I have found also seem high (60 to 80) but perhaps reflect those times when she was an independent merchant ship and needed all guns and of course gun crews.

Unless I lose my favourite marbles, I will build Mediator as per the drawings. The only planned exceptions to this are details, such as to substitute metric standard plywood sizes for the main former and bulkheads, the addition of a capstan and some changes in the deck layout and planking, more on that later.

Planned materials: woods = ply, cherry, castello boxwood, apple, holly; other materials = brass, card, paper and miscellaneous bits as inspiration requires.

There is a back-story. I have never made a wooden model ship. After years of planning to build HMS Pickle from scratch, when the time came to start making sawdust my expectations (thanks to MSW) had grown to the point where the bar was much higher than I could achieve with my untested skills. So, as a part of the learning process, I decided to make at least some of my mistakes in a safe place. I am making Mediator as a sacrificial model that will allow me to rehearse processes that are new to me and (hopefully) still have something acceptable at the end of the exercise. In other words, I am going to build a model before I build the one that matters to me.

Since this is a hobby, not a career or a marriage, it is worth admitting that I felt better about the Pickle project as soon as I took the pressure off by doing Mediator first. Who knows? With plans of such quality as a starting point I may end up with a decent model. If not, it will be down to me as there is nothing wrong with the plans.

So, here goes. Sawdust begins in post #2.

Link to post
Share on other sites

The seven A1 sheets of plans were printed by a local shop. Three of the sheets are now hung above the workbench, one was cut up to make the formers, bulkheads and a few other bits. The rest will not be needed until the build progresses.


The cut out pieces of former and bulkhead drawings were scanned for future access since the originals would be glued to the plywood and lost. Before going any further I printed out the scans to check that they still matched the originals and KAPOW!! they had been reduced slightly somewhere in the digital processes of my scanner. Reprinting at 101% gave a perfect match. This is important as will be seen shortly.

The plans called for 3/16th inch ply for the main former and bulkheads but I compromised to use available material. I settled on making the main former of thinner 3.8mm material and the bulkheads of 5.5mm ply.

Irritatingly, the piece of 5.5mm play I had turned out to be just too small and one bulkhead had to come from a slightly thinner piece. The cut-out drawings were glued to the ply with spray adhesive (note to self: wear gloves next time).




The bulkheads were cut out on the bandsaw (second note to self: just get a bigger piece of wood next time, they were too crowded to handle comfortably).


I left the paper on and made notes if there was a possible low spot or other boo-boo.



Each bulkhead is drawn with the ‘top timbers’ in place and I was convinced that it would be easier to make these separately instead of as integral (and vulnerable) extensions so I omitted them and left notches for each.


The main former required planning. Being the backbone of the hull, it was cut to profile as accurately as possible. The throat on my bandsaw is not deep enough to allow all the slots for the bulkheads to be made consecutively from left to right: starting from the stern (the left hand side as viewed in my print-outs) most of the slots could be cut but then the stern starts to foul the body of the saw. I cut as many as I could, printed out a mirrored image of the scan of the bows end of the former, checked for accuracy of size (whew!) and trimmed closely to profile. Using the already cut slots and a bright light for registration, the mirrored image was glued to the opposite side of the former.








A single test cut established that the two drawings were in pretty good registration and I was able to finish the slots from this side.













Trial fitting of all pieces revealed a few tight spots. Out with the hand files, feeling pretty good.

After over two years planning and drawing Pickle, it is very telling that a mere nine days after deciding to build Mediator I have a build log.

Link to post
Share on other sites

Getting the plans unstuck from the former was pure misery. The spray adhesive was a cheapo from a bargain store and in some places dried rock solid: I will not be using it again.

Next gripe: the supposedly straight line at the bottom of the former where the keel attaches had an inexplicable curve in it. It was only a tiny bit but it would prevent the keel piece from sitting properly so it had to go.

A sanding jig was improvised by temporarily fixing the former on a steel plate (a base for a small lathe) and lining up the bowed edge of the former with the straight edge of the plate.








80 grit sandpaper screwed to a square stick and run along edge, which is also known to be square, produced the straight 90 degree edge I needed.











Straight line achieved.

Link to post
Share on other sites

The deck planking of Mediator is laid on top of a sub-deck: the main and quarter decks are each drawn as mirrored images and the four pieces that make them up are cut from thin plywood. Each is notched to accept the bulwarks extending upward from the bulkheads. There are no instructions but I saw an opportunity here to ensure the sides were symmetrical by cutting the two pieces in one operation. In some vague sense I also felt this symmetry would pay off when it came time to deal with the top timbers.

Cutting thin ply is no hardship on the bandsaw with a good blade but there is always some degree of tear-out unless precautions are taken. Bringing the pieces to be cut tightly together and mounting them on a sacrificial plank greatly increases the odds of success.

I started with the main deck pieces.

Double sided tape is used to first attach the workpieces face-to-face.






Next the plan was glued to the top piece of ply, aligned to the edge.





and the assembly screwed to the plank. It looks like overkill but with all those notches to cut the possibility of ‘chatter’ is high unless these steps are taken. Cutting proceeds very slowly.

The outline shape is cut first, the waste part of the plank is now discarded. The notches can now be cut easily.






After cutting was complete, I unscrewed the workpiece and carefully prised apart the ply deck pieces.





Link to post
Share on other sites

Mediator looks an interesting vessel, I shall follow along with your progress. 

I downloaded these plans with all intents to do it myself but got waylaid by Winchelsea 🙄

I like the idea of cutting the sub decks pieces together,  so if it's ok I'll log that for future use 

Link to post
Share on other sites

All shaping and fettling of the keel, stem and sternpost is done now before gluing the bulkheads in place. For the ‘1/4 inch material’ specified for these components, I am using cherry.

Starting at the sharp end, the components are a stempost comprising three pieces. Probably due to the circular shape of the finished item, the stem gracefully butts to the keel without either deadwood or rising wood. Close examination of the NMM plan reveals nothing to contradict this so, again, my compliments to Jeff Straud for unravelling this aspect of the plan.

The keel: the height tapers from thick at the fore end to less at the stern. I also will model the taper fore and aft of the width although it is drawn with parallel sidings. A false keel is fitted and it’s depth is provided for in the shape of the stem where the two meet.

The sternpost is one piece and straight with a taper.

The finished keel will have a single scarf joint, a taper in height from the stem to the stern, and a taper in width at each end. I think I know how I am going to tackle this combination of angles but will take stock when it is on the workbench. For the record, the plans as drawn do not include the taper in width. This is my take on practice of the time.

I cut an overlong piece of cherry 6mm x 11mm on the bandsaw and spent a couple of minutes sanding it to a smooth finish. Before any shaping or trimming to length, first comes the keel’s scarf joint. I cut it at approximately the right spot and milled the two pieces simultaneously. The result seems acceptable.






Here is the glued scarf after sanding. I hope it will not be a weak spot considering the handling and fettling needed for all those angles I just mentioned. I used a dab of acrylic paint in the PVA glue and it worked but I had hoped for a more crisp line to the join.




To taper the length of the keel piece I needed a jig.

The taper was achieved by removing material from both top and bottom faces of the keel piece. The stern is about 4.5mm thicker than the stem and, by my laboured calculations, the new top and bottom edges would pass through the butts of the scarf at the correct spot to leave a scale-correct appearance. I spent a few tense minutes lining up a straightedge to test the theory and eventually relaxed.

A piece of steel strip a bit longer than the workpiece was the starting point. It had straight, parallel sides with a clean, un-nicked edge. Double sided tape was placed along one edge.




The long keel-piece was laid carefully in place with the unwanted material overhanging the edge and pressed into the sticky tape.





Next, I took this little ensemble to my home-brewed thicknesser which was already set up to match exactly the width of the steel strip. The right-hand edge of the steel travels along the fence, the left just barely touches the rotating drum: the material hanging over the edge is removed.






With one side down and one to go I was pathetically pleased to see the new edge passed through the butt end of the scarf exactly where it should.




After carefully prising away the keel (mind the scarf!) I left the tape on the steel. After marking the other side of the keel piece and mounting it as before, re-using the same tape, I ran it through. It worked.

The emphasis was more on getting two straight lines rather than a smooth finish as neither face will be visible, only the sides. Key to success: running the drum at high speed. I used 3500 rpm.

Link to post
Share on other sites

After agonising over the rights and wrongs of the two options, I decided to attach the keel, stem and sternpost after installing the bulkheads. It may be obvious to others but it certainly made me think about how scratchbuilding is deep water.

Next up is the stem. The wood in this group is cherry except the false keel and all shaping and fitting had to be done while it was still possible to lay the hull former flat on it’s side.

The plans were stuck to the cherry in line with the grain.






The earlier experience with an over aggressive spray adhesive is history: this is my new go-to spray adhesive and it works like a charm. It is strong but in one of those mysterious ways that only chemists can explain it is also temporary. For about 24 hours after initial application you can peel away the paper and clean away the residue with a touch of IPA.





Once the pieces for the stem were cut out on the bandsaw and tidied a bit, the scarf joints were milled.






This worked smoothly but I realised I should have left more waste area around each of the pieces when I cut them out as there was no ‘second chance’ should I have wanted to re-do a cut by even a tiny amount. No problem, but noted for next time.





I did not attach the pieces to each other until the individual pieces sat properly in their position against the former.

I marked the former where the scarf between the stem and keel should be (the transition from curved stem to straight keel) and worked from that. This allowed me to offer up the lower of the stem pieces and make a mark where the upper scarf would fall and everything else followed from that.





Fitting and fettling of the first two pieces done, I glued them together and started to repeat the process for the final bit of stem. This was mostly just a process of offering up and making a lot of small tweaks. It was important to get the curve right on the front edge: the line of the curve will be continued as a straight line giving a taper in elevation to the false keel. Easily done by using a copy of the drawing as work board. The stern post is also ready and I will trim it to join the keel when they are all fitted to the former.


Now I can move on to the bulkheads.


Link to post
Share on other sites
  • 2 weeks later...

Been working on the bulkheads for Mediator.

After getting the outside profile of all the bulkheads correct I turned to their tops, which support the decks. I really did not like the thought of truing up the lines of all 19 individually so I made a jig gizmo to semi-automate the process.


I will post details soon in the 'tools' forum.

The workpiece is fixed to the arm and then the whole assembly pivots on the pin (lower right).




Bulkheads are held by an improvised screw-down clamp.




Gives a good finish ...




... and consistent results.




I should have the bulkheads assembled soon.


Link to post
Share on other sites
  • 2 weeks later...

It has taken a while for me to get the bulkheads fitted. During the assembly of the bulkheads a twist appeared in the hull former. It was about 6mm out of true and several bulkheads were already in place.

I had ensured the initial assembly was square and true in all directions:





However, the twist was there and it was too big to ignore. I looked at the scraps of the plywood I used to make the former and, sure enough, the remainder had also developed a bow. Since I chose the blasted piece because it was perfectly flat when I checked and now both the workpiece and the off-cut were warped it cannot be a co-incidence. I was satisfied that the material was the problem and not something I had done.


The bulkheads already fitted were in the middle as I had started with these wide stations and had planned on then doing two bulkheads at a time, one at each end.


If I could correct the problem without removing these pieces then I would carry on, otherwise I would chalk it up to experience and start again. It was time to get creative: I resorted to force.


The idea was this: if the bulkheads were parallel and also at right angles to the hull former, then the hull former must be straight.

First step was to go back to the beginning. I measured the gap at the junction of the former and the bulkhead: the gap should be the same all the way across but it wasn’t (it was when I installed them, the twist happened afterwards. @/$*&!!). Spacers with good square faces were made for each gap matching the measurement taken at the junction. I used a variety of materials: cherry offcuts, plywood, birch etc.

Each gap was different so it was a slow process. I paid a lot of attention to getting the spacers the exact width of the gaps, sometimes making the spacer by laminating pieces together for a good fit, sometimes running pieces through a thicknesser for tuning. Typically the same spacer that was a loose fit on the port side was tight on the starboard so I used whatever force was necessary to get matching spacers ‘home’.









Once the fit was as near to perfect as I could manage I glued and clamped. It was heartening to see an improvement (small but in the right direction) after the first couple were done.


Most of the twist appeared to be in the rear half so that end got the heavy handed treatment.





The result is not pretty but it is straight and I was glad to pull it off. It definitely does not look like I envisaged but … so what?












Mediator has a cabin at her stern: the last of the bulkheads form the structure of this space and I will come back to these after a while. I have some unresolved thoughts about how I will detail the cabin entrance and want to ‘dummy-up’ a couple of trial pieces before gluing anything. Maybe after fairing, maybe after planking, we will see what seems right when I make some more progress.





An unexpected advantage of posting a build log is that I was shamed into clearing away the clutter from the workbench before taking pictures.






Link to post
Share on other sites

In post #6 above I made the subdeck pieces out of some really nice modelling plywood. This turns out to have been a mistake. The subdeck pieces must bend to conform to the curve across the tops of the bulkheads and the plywood I used was just too stiff. Experiments with the offcuts proved that it would not work without excessive force and, rather than start trial and error bending with heat, it was just easier to remake them.

A piece of inferior plywood was chosen as best for the job (didn’t think that would be part of the story) and the same process as before was used. I was able to simply use one of the existing subdeck pieces as a template for tracing the profile.











Prising the two pieces apart. I love that 3M spray adhesive.








Just sitting in place to get a feel for the next steps. This plywood will bend easily, should have used it to begin.











I am still getting used to the look of the hull/bulkhead assembly with the spacers. It looks like something out of Barnwood Builders. However, I will have plenty of places to get a fixing for the subdeck pieces :) .





Link to post
Share on other sites

Mediator is fighting me. I am winning, but it is important that I do not underestimate the ability of Mediator to lay an ambush.


The new sub-deck pieces (see last post) have to bend in two planes to sit properly. They were made of an inferior plywood that appeared easily bent. A test run revealed splits in the surface and de-lamination after being bent and left overnight, so it was the end of the line for these bits.

Fortunately I still had the original sub-deck pieces made of superior plywood. To get them to bend over the bulkheads (which was the reason I had rejected them) I cut a series of grooves in the underside to allow the stiff ply to bend. For some reason I imagined that the grooves were not needed right up to the edge where the two halves would meet. Stay tuned…











To hold the two halves in their new shape while the Titebond worked required clamping. Due to the compound curves I needed to improvise something that would hold the centre edges straight, pull the width onto the curve of the deck across the tops of the bulkheads and keep whole kaboodle true to the sheer. These are the clamps I made from the type of small screw-in eyes used in picture hanging and 2.5mm eyelets:





Pilot holes were pre-drilled in the deck pieces but not into the bulkheads in order to get the most out of the gripping power of the self-tapping threads.





They were screwed in with fingertips.





Started in the centre on the hull centre line and worked towards each end. Once that was done I improvised a hold-down clamp like this …




… on the centre line until the whole line was tightened down. Then, a bit of force to pull the outer edge down. Lots of glue, worked quickly …









… and let it sit for a day before unscrewing.






The whole thing worked and was as solid as I could have hoped for, but the centre join line was proud where the ply had resisted bending.





This was due to my bright idea of not cutting the grooves near that join. To be safe drove a few pins in before about half an hour with 80 grit sandpaper wrapped around a sanding sponge to fair the join.









That's all for now.




Link to post
Share on other sites
11 hours ago, Edwardkenway said:

On my Cutter I shelled out for some .8mm ply from CMB, a tad pricey for 600 x 300mm.

Thanks for the kind words. I try not to think of how immaculate your cutter looked at this stage compared to my build.

I started with a plan and the issues I have had so far all stem from my choices of materials. I will tread carefully from now on.

There is still a quarterdeck and cabin roof to do for Mediator and I have been playing around with some materials, dummy-ing up the parts in card to see if I can predict any issues with different thicknesses of materials.

Heaven forbid I actually have to buy something.

Link to post
Share on other sites
  • 4 weeks later...

Sort of an update: Mediator has been on hold because I unexpectedly had to use the work bench for a sudden domestic job. This prompted me to make a box to hold everything in one place until the shipyard is re-installed, hopefully in the next few days. I have sorted out some of the old material that caused me a headache by twisting. It is in the bin.


The break from the project has had a positive effect: I am itching to get back to it. Also, the bashed hull has remained stable with no sign of the warp re-appearing or the sub-deck 'pinging' out of place.

Link to post
Share on other sites
22 hours ago, Jim Lad said:

Just found your log, Bruce This looks a really interesting project.




 Thank you John, I have used the time Mediator is off the bench to dig around for more of her history. It has lead me to some mildly surprising conclusions, number one being that there were squillions of small commercial vessels at the time and there were very few records. I am hopeful of finding out more of the circumstances of her loss when I can get back to the National Archives in person, but who knows when that will be?.

Been pondering whether to make a ship's boat for her. There is a small work surface in my study I could set aside to tackle the task as a separate model. With winter banging on the door this suits in many ways.





Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Create New...