harvey1847

Hello Ed!
 
Wiht that "cadency" of frames I am sure that you will end the hull in two moths or so...not two years!
 
 
Look what I have found about the treenail question. I have tried to translate it the best I could. The sketches talk by themselves but the way it was done in the XVIII century amazed me. It is the Rooth system, around 1752.
 

 
(1) A drill is made that pass through the external planking the frame and the interior planks; A treenail of the same diameter is then selected (for a “B” treenail type in this case*) except the head of it which is a few inches bigger; the length of the treenail should be one foot more than the hole drilled. The treenail is spread with lard and is introduce (2) with a hammer. When we reach to the head where the diameter is slightly more, we need to hammer strongly, that’s why the head is reinforced with spunyarn rope, this avoids the treenail to split. When it has been introduced to the maximum and it extends on the inner side, both heads are trimmed to the face of the planks (3) then a treenail wedge or spile is force in both sides of the treenail (4-5-6) so no free movement is allowed.
 
The sketches of the “blind treenails” talk by themselves so I am not going to translate the text of the same period.
 
 

 
Beautyful work and posts like always.
 
 
Daniel.

Hi everyone!


I think this might be the shortest post I
put on. I am just happy to been accomplished at least two of the filling
transoms #4 & #3.  I have repeated
four times #4 and twice #3. Fingers cross.


My intention is to put some kind of rising
keelson fronting the inner post and the five transoms. It´s my intention,
another thing is if I will be able to do so with the tools I have right now.


The pics show how I fail treating to finish
the FT#3 by itself. I founded that sanding and chiseling it before been cut
from the whole piece of wood was easier. The piece is quiet weak. I have also
bevel a little bit the inner post to “receive” the filling transoms.


 


Daniel.


 

My next project is the Chaloupe Armee en Guerre or Longboat Armed for War. This will be a scratch-built model at a scale of 1:36, from the plans available here: http://www.ancre.fr/vaisso25.htm.
 
I ordered my copy of the monograph and plans direct from ANCRE and they came speedily and at a very reasonable rate of postage. This is the first publication from ANCRE that I have seen, and I must say I'm impressed. The six sheets of plans are drawn beautifully and the accompanying booklet, which describes the boat and the construction process, is very well laid out. There are many illustrations of the construction process, as well as detail photos of a 1:18 version of the same boat. I should note that the original text was in French and has been translated into English by David H Roberts, who has done an excellent job.
 
 
 
Whilst finishing my Agamemnon (http://modelshipworld.com/index.php?/topic/1115-hms-agamemnon-by-decoyman-caldercraft/) I have been collecting pieces of wood I thought might be useful when scratch-building. I discovered The Toolpost (http://www.toolpost.co.uk), a treasure trove of woodworking equipment, in Didcot, about 15 minutes drive from where I live. They have a good selection of hardwoods and fruitwoods, mostly in turning blanks, as well as a selection of pieces of boxwood of varying sizes. They were also happy to cut every piece I bought into 1" slices on their bandsaw. This means I can now machine them to exact dimensions on my Byrnes table saw, which is a pleasure to use! I haven't finally decided which woods to use where, but I'm starting with apple for the keelson and ribs and will probably use cherry for the planking. I acquired a box full of odd pieces of wood, including a large amount of ebony, from eBay for a very reasonable sum: I might try turning one of the ebony pieces to make the large bow-mounted cannon.
 

 
The picture above shows (from the top) ebony, apple, box and cherry.
 
Before I could get going on the good stuff I needed to make a mould, over which the basic hull will be constructed. The instructions say to make this from 5 mm ply, which actually measures nearer to 4.5 mm thick. Unfortunately French plywood is not available in England; here we have 3 mm and 6 mm, which isn't much use. In fact the nearest thing I could find was 4 mm MDF, available on the internet in packets of ten 400 x 300 mm sheets at a reasonable price. This is still not thick enough. The mould is made from layers cut to the shape of the waterlines, if the layers are too thin then the whole boat will end up compressed vertically.
 

 
My solution was to interleave the MDF with layers of 0.5 mm cherry veneer, which I happened to have around, so that each layer was 4.5 mm in total. There were some benefits to this method: I could glue photocopies of the plans to each piece of veneer and then cut out each layer accurately using a scalpel. Once that was done I coloured the edges with a black permanent marker. This was so when I sanded the mould to its finished profile I knew that when I reached the black I was nearly there.
 
    
 
The next step was to glue the veneers to the MDF and remove the photocopies. I left them to dry overnight, interleaved with cling film and weighted down, and then cut each MDF layer out with a fret saw, slightly larger than the veneer stuck to the top. Each layer was drilled on the centreline at stations 5F and 5A and then stacked up and glued in order with dowels in the holes to provide alignment. I used dowels instead of the drill bits because I could sand the dowels along with the MDF.
 
    
 
There was a lot of arm-aching sanding to bring the mould to its final form. I used a Surform for quick removal and then coarse sandpaper on a block for accuracy. The end result was pretty accurate but not perfect.
 

 
To check the profiles while sanding I glued copies of the frame profiles to 1.2 mm card, as well as the keel. I used these to check I was getting the shape right, but I also cut them so they would slot together. Once the mould fitted all the card frames and the keel I was just about done!
 
  
 
In the last of the photos above you can see marking out for the recesses to take the keelson and the knee of the stern. To ensure the keelson recess was the right size I made a start on this piece. It's cut from a piece of 2.3 x 6 mm apple on the table saw, which I also used to cut the rebates for the frames. It curves up towards the stern so I soaked it in hot water for a while, then taped it to the mould.
 
   
 
Once the keelson had the correct profile I used it to adjust the recess in the mould. The last thing to finish the mould were two coats of varnish and a polish. The purpose of this is to protect the markings showing the frames and the wales and to try to stop the glue sticking the frames to the mould. We'll see how we get on with this in due course.
 

 
In the meantime the next task is to bend the frames round the mould.
 
More soon!
 
Rob

Hello again friends,
 
Today was more exploration of the conning tower.  Instead of just building the con without any working detail I "conned" myself into going hog wild.  That's why I am now taking my time to draw up the basic build as "plank on frame".  I must be sure about where all the detail stuff is placed and the measurements.  I'll have to go back to my drafting table and lay things out for this build.  It's like Remco's mantra, treat each part as a model.
 
In addition to more thinking and sketching I painted both the stern and bow torpedo loading wells and tubes.  I also made the stern well hatch doors.  Then, in my sketching the conning tower I determined that I had to remake the dingy loading boom, which is also the center support for the hatch covers.  
I have no detail drawings for this thing but have a fair idea how it could have been done.  For the model it'll be attached to a rotating pin at the aft end of the conning tower and can also be rotated out of the dingy compartment with a bolt through the rotating pin assembly.  The other end will have a place for a sheave and tackle and a latching hook for the lift cable.
 
I also made two of the stern mooring thingies.
 
Well, that's about it and below are a few pics of today's progress.
 

This is the stern torpedo loading tube installed and painted.  The entire well is painted dark grey.
 

This is the bow torpedo loading tube installed and painted with the pressure door closed, as well as the entire well area.
 

This is the bow torpedo loading tube installed and painted with the pressure door open.
 

Here are the two mooring gismos at the stern.
 

Just for doing something else I made the lid for the mine tube bins.  Still tempting to actually cut a hole in the poor boat and install a tube with a model of a mine.  Just too much work, the area inside was not build with that in mind and it'll require a lot of very difficult work to make it look right.  It's like doing an appendectomy through your nose.   But then again, who knows, I love a challenge.  Don't get your hopes up too high John   
 

This is a copy of a photo I have of the O 19 with all the mine bins open.  I modeled my lid after this picture.  My question is this, if anyone can lead me to a place that sells letter and number decals that look like these I'll be mighty obliged.  I also need Roman numerals for the draft markings.
 
Cheers, 

Thanks Duffer.
Your right Joe.....
 
So I continued and didn't change the mortices. Getting the round up of the deck into this special beam took some patience...
 

 
Remco

Hello everyone and I trust all y'all are doing fine and being in good spirit.
 
@ Mark, locks on the hatch doors?  They have locks?  Oh noooo, more work, hinges and locks.  I thought locks is a preserved fish      Oh, sorry, different spelling.
Talking about hinges for the hatch doors I am making, I need 25 pair.  They are to be made from 1.5 mm brass tubing cut into 1 mm small pieces.  That makes 50 of these little buggers.  That'll keep me out of the bar     
 
@ Daniel,  painting the tubes and locking wheels is coming soon.  All of the "stuff" inside the wells will be painted dark grey.  I'll leave at least one well and door open showing the loading of a torpedo.  I think it'll be the forward one.
 
@ Adriaan, thanks for your approval, yes, I'm happy with the way they turned out.
 
@ John (texxn5), thans John.  Yup, I have figured out how to make the AA guns retract into their-water tight pressurized tubes.  how?  Glad you asked - - - - - first I insert a brass tube into the pressure hull with the end even with the top of the pressure hull.  The length of it must be long enough for a second tube that can slide into the lower tube, much like a hydraulic car lift.  On top of the second tube will be a cross beam to keep it centered and the base for the AA guns. This way the gun can swivel up and down and rotate horizontally.  Now, that's what I see in my mind right now.  Next I'll have to make a work sketch and put some measurement on it.  I just bought a few brass tubes for this project as well as a few smaller tubes for the periscopes.  Hmmmmmm, yea, they'll retract too 
 
@ Remco, Sinter Klaas?  Oh my, I have not been a very good boy this year - - - - I hope "Zwarte Piet" wrote all my bad things with invisible ink       I hope you realize that I didn't mention it as a hint - - - but it would really be great to know what sort of anchor they used on the side.
 
@ Ian, well, that's what happens when you go away for a week and don't log in to MSW.  Things change rapidly.  Well, this morning I had to remake the stern loading tube and grind some more wood away in that area.  Took me about an hour total.  Both tubes are now cemented in place and I can paint the wells and tubes.  Tomorrow we'll have a few pics.    
I have drawn the outline of the con on top of the deck but I may have to make it a tad narrower yet.  I'm following the deck layout drawing I got from Gino.  First I used the O 21 model drawings I bought through Remco but the O 19 and O20 seem to be narrower then the later subs.  Hey, I am also learning about subs, I'm an airplane guy   
 
I'm still waiting on my 17 mm tubes for escape hatches.  As mentioned a few posts ago, I will be making my own AA pressure tubes from flat stock.  I don't see paying $25 for shipping.  I also started with the net / cable cutters for the bow.  
 
Well, that's it for today.  Thank you all for joining me on the build of my father's boat, the O 19.
 
Cheers,

a little trick.
to catch small parts, I use a small box that attaches with a magnet.

cannons start 6 L

Helloo Boys and Girls!
 
Still working and alive. i do not Know what is harder to make, CAD drawing or sanding frames...
 
If I end this who Knows when,,, I will gift myself a present like a plastic ship in a nice beautyful box, with intructions to read, plans of how to be painted, some decals and thousands of pieces numbered...
 

 
I have been drawing since yesterday. Now I´m going to sand and sand again.
 
best wishes to all!
 
 
Daniel.

Hello Boys and Girls!!
 
 
I have finally been able to set all the square frames from #19 to the one before the fore cant frames. In the last post they all were set but not with the spacers. It has taken me three days to put all that little pieces of deadwood on the keel and the top platform. It has been really fun. The ones on the upper wood are already glued. Different widths but all measuring 35mm. I glued them putting the PVA on the wood with a little brush, not to the little piece of timber. I removed immediately all the excess with a wet brush. The ones on the keel are glued with “scholar stick” that red one so well Known. I will remove all this chocks on the keel because…
 
Some poor pics.  (updated, no more skipe around!!)
 
 
 
 
 
 
As you can see I have not glued the gripe and the fore pieces. I have to bevel it. I will glue it at the end sanding at the same time the keel and the gripe.
 

 
 
There is a lot of gaps between the frames and the top board so I will glue them to the keel first. With rubber bands I will tight them to the platform and glue a timber on the top of the frame. Back to post #9.
 

 
Next step, the fore cant frames. It only took me two years and three months to get here…and here they are (updated)
 

 
 
Best wishes to all.
 
Daniel.
 

Young America - extreme clipper 1853
Part 18 – Framing Continued
 
 
American Clipper Note:  Flying Cloud was launched from Donald McKay’s yard at East Boston a month before Challenge.  She was of comparable size, and like Challenge, bound for California from New York on her maiden voyage.  Inevitably she was drawn into the great “challenge” surrounding the ship Challenge.  She left New York in early June 1851 under command of Josiah Cressy. Three days later she lost her main and mizzen topgallant masts, but reached the line (equator) in 21 days.  She arrived in San Francisco in 89 days 21 hours, beating the previous record of 97 days, set by Sea Witch the year before – and 18 days under the Challenge’s ill-fated maiden voyage performance.
 
After the last post, there was a question about the dark glue that I use to highlight structural joint lines.  The 8 oz. bottle I mixed up for Naiad was just about empty, so when replacing it I took some pictures to help answer the question.
 
The first picture shows the starting point, plus two bottles of ready made dark Titebond glue.  The new bottle to the right is the currently available dark Titebond II.  I find it a bit light for pear.  The old – quite old actually – bottle in the center is the old Titebond dark glue – just about the right shade but no longer available.  T the left is an 8 oz. bottle of the standard yellow.  (The first thing I do with a new bottle of Titebond is pull off and toss the sliding top, cut off the closing nib and insert a length of plastic rod that is easy to remove and replace and does not clog up.)
 

 
At the front right is a jar of raw umber artist grade pigment that will be used to darken the glue.  This bottle is several lifetimes’ supply.
 
 
In the next picture, about a teaspoon of dry pigment was added to about a tablespoon of water and is being thoroughly mixed with the pestle-like Teflon rod until there is no sign of powder or lumps.
 

 
The entire 8 oz. of glue is then added a bit at a time and mixed in.  The next picture showsthe final appearance.
 

 
In the next picture the empty bottle has been thoroughly washed out with hot water and is being refilled with the darkened glue.
 

 
I expect this will be enough to finish the model.
 
The next picture shows the last of the full forward square frames.  The rail stanchios are about to be installed.
 

 
The frame is now ready for beveling.  In the next picture the forward face of the pair is being trimmed back to the forward profile line on the disk sander.
 
 

 
The aft outer profile was previously trimmed back.  The disk is kept away from that line in this step.  This leaves a hump or ridge between the two profiles.  The next picture shows this being removed by hand with a flat Rasp.
 

 
The last picture shows the resulting bevel.
 

 
The insides are only roughly beveled – mostly using a spindle sander.  They could be hand finished as well, but I intend to do that after the hull is assembled.
 
The final bevel will be refined when the hull is finished sanded.  Beveling these pairs before assembly saves tedious sanding work later, makes frame erection easier and yields a more accurate hull profile.
 
There is still some work to do on these frames before erection.
 
Ed
 
 
 

No II arrived yesterday in the mail have not put it down since except when my wife yelled at me that it was past time to go to bed!!! She was asleep when I finally got there!
 
As you promised EdT well done
 
Guy

Again, thank you all for the supportive comments.
 
Allan, sounds like a good project.  The full framing would give you a chance to exercise those TurboCad skills as well.  Anyway, I am glad to hear of your interest.  I have been hoping the YA build would attract some from the fully-framed set. The framing is different from the 18C RN.  It is alot simpler - no chocks, standalone frames, jogged or curved toptimbers and no ports to contend with.  At the same time there is more of it.  There are also more judgements to make on design specifics.  Although quite a lot is known and documented on the general construction, specific ship structural details have been lost.  Good luck.  Let me know if a novice can help.
 
Bruce, the framing is going faster than I expected.  I spend on average 2-4 hours each day in the workshop, often in more than one session.  I also spend time outside the shop - on research, drawings, photos and this blog.   When I start to tire, I quit and do something else.
 
The Sovereign / YA race would have been interesting.  In reading the endless accounts and passage times for these various ships and routes, it appears to me that the abilities of the captains and the vagaries of the weather - especially time of year conditions - had as much to do with performance as the differences in the ships in this class - probably more.  Variation in sailing times over the same routes are considerable for the same ship on different occasions.  My impression is that Babcock, YA's original skipper, may not have been the man to beat Sovereign.  On that first 110 day voyage to SF, it seems he made some judgements that extended the time, but I have not dug into that. 
 
Your comment on the iron strap bracing caught my attention, particularly your positive statement that it was on the inside.  I am inclined to agree, but in scouring every source I can find, have not found a definitive reference.  On Crothers Challenge drawing, dated 1975, it is clearly shown and noted as on the outside - the so called Lloyds system.  By the time of his book (1997) he seems to have backtracked and is not sure.  Most of the ships he lists have the bracing on the inside - the Admiralty system.  But none of those are Webb's.  He discusses all this.  I believe by the 1860's the American Lloyds registry specified outside, but in the 1857 registry inside bracing is specified.  Structurally, outside bracing is better, but more troublesome to install.  I do plan to install this and am leaning - currently - to inside.  However, my question is, do you have a reference for this?
 
It is unfortunate that Great Republic, as designed never got a chance to show her performance.   After the fire - before her first voyage - she was cut down and given a smaller rig - but was still a good performer.  Young America also had a very long - and essentially trouble-free - career of 32 years with the 50 punishing Cape Horn passages before she was mysteriously lost on her way to Trieste from Phialdelphia in 1885.
 
Thanks, again, for your interest and comments.
 
Daniel. I made some new dark glue and will show some pictures in the next part.
 
Ed

Can not wait to see those wheel rims painted!
 
Beautyful work Piet.
 
 
Daniel.

I own the AOS Pandora book and looking at it I can see that WANG did all of his decks from that book. I do not know which would be more accurate for the Triton - Pandora or Diana or something else altoghter. The drawings for the decks supplied by this website do not show much detail, just the overall location of the rooms on that deck. I plan to use the Pandora drawings whenever there is a lack of information on the drawings supplied by this website. When the model is completed it will look good but may not be accurate.
 
Richard

Ed I have never ever thought about building a clipper.   I was OK watching your  first posts and was enjoying just looking at the great work. But now that the framing is coming along you have gone and messed up my schedule big time as I try to figure if I could juggle my projects to fit  in such a project over the next few years. 
 
Great work Ed, on all counts.
 
Allan

Hello every one.
 
Been busy making the torp loading tube door locking wheels.  I turned a wooden dowel to the correct diameter and then wound a .7 mm brass rod  around it to form a coil.  That way I could cut a pice that's circularly formed.  Okay, now I have the rim of 10.5 mm.  Next I cut a few small pieces of the same diameter rod for the spokes and soldered them into a cross.  I cut and filed the ends to fit inside the rim and soldered it all together.  Yes, I used the steel office clamp as a heat-sink.
Filed and scraped excess solder away but the photo tells me I need to do some cleaning up.
 
I also made the hinges for the read pressure door and now both tubes are ready for assembling and paint.
 
I also cut and installed the small pieces of wood for under the deck plates at the stern torp loading well for the hatch door hinges.  When that is all nicely trimmed both the bow and stern wells are ready for paint and installation of the tubes.  Then it's making busy with the hatch door hinges.
 
It's amazing how much time goes into making these small items.  Well, here are two pics of today's accomplishments.
 

Here we have both the bow and stern torpedo loading tube assemblies displayed on to of the deck.  In the meantime I have painted the inside of the tubes flat black  That penciled circle between the tubes is the future location for the deck gun. 
 

This shows the result of winding the brass rod to make the little wheel rims.
 
Cheers,

The next step was to make jigs to space the upper deadeyes above the lower. I used a line attached to the masthead to get the angles of the shrouds lined up with the lower deadeyes. This will make sure the the two levels of deadeyes are parallel. I used plastic sheet and drilled holes through each deadeye through the plastic Then a second pin in a side hole of each to keep the deadeye from spinning. The bottom row has wires holding the plastic down in place at each deadeye.
 
I started with the mizzen due to the way the mizzen forestay runs. It had to drop down a deck level going through a bullseye attached to the rear of the masinmast, down a bullseye at the deck right behind the pump.
I've mentioned that this is my 2nd rigging attempt. Originally I had put a thread through this difficult to reach bullseye before installing the pump so that I could glue it to the stay and easily run the stay later. But now I had to thread this line down in there past all those fine railings and pump wheels without bending and wreaking them. Yup, it was difficult.
 
Bruce

The door has a wire stretched across the to to tie my rigging onto for pre-stretching. [Turn motor sign is a reminder to keep turning the crank over a few times now and then on the engine that is still good from my last motorcycle crash which totaled the very expensive show Harley I'd spent 3 years building.]
 
And that is my rope walk. A band of crazy Gypsies came through and built it out of assorted junk. [Not really.]
 
The can has Conservator's wax thinned out to make a bath for soaking my rigging. My standing rigging is dyed with India Ink cut a bit with water. Running rigging with F&W acrylic ink- raw sienna with a bit of black in it.
 
Bruce

Frank...if Bruce doesn't mind..here is a link to some of his building of the Lightning.
 
http://www.vonstetinaartworks.com/id26.html
 
Rob

Thanks, again, everyone.  I am really looking forward to seeing the full hull in frame.  The bare frames really let you visualize the shape.
 
Daniel, there is no secret to the messy process of making the dark glue - if  you have Naiad Volume I (subtle hint).  The process is simple.  I use dark brown artists' pigment.  Mix it well with maybe a tablespoon of  water - less than a teaspoon of pigment will do - to obtain a dark liquid - no powder or lumps visible.  Add this to a six ounce bottle of PVA (I used Titebond II) and mix it in thoroughly in a bowl - a mortar and pestle type of mixing - until it reaches a smooth syrupy state - about the color of chocolate milk or darker.  Wash out the remaing white glue in the bottle and refill it with the dark glue.  One 6-ounce bottle saw me completely through the Naiad project.  My glue is very dark and could be lighter with the same effect when dry.  I have had no problem with adhesion.  I am about to make a new batch so I will include some photos.  Good timing on the question.
 
Ed

Nice Piet,
 
But one question......
How do you find that sub on that worktable????????
There are so many stuff on it         
 

Hello everyone, and thanks to Yambo,John (texxxn5) and Sjors for dropping in.
 
Well, today I made the brass rails and support pieces for over the launcher deck area.  I also completed the mounting block for the stern torpedo loading tube and installed same.  I'm now ready to finish the well opening and add a few strips of wood for the hatch door hinges and paint the inside of the forward and rear well areas.  Hope I have enough paint.  
Then I cut three small pieces of tubing for the pressure door and soldered the one to the tube.
 
Next I tried to make the door locking wheel but had some problems with it.  Very small to work with but I'm not giving up.  I need to have them finished before I can solder the hinges to the door.
 
I'm still waiting on the 17 mm brass tubes for the escape hatch tubes.  I like to have them before I can definitely know where the deck rails go.  This too will be a tedious job to cement them to the deck.  But there is still a lot of work to do before I can do that.
 
Here are two pics of some of the things I did today.
 

These are the brass real and deck support beams/rails over the launcher deck area.  The two forward ones are for the deck support, the four behind them are for deck support on the outboard side and hatch covers between the rails..  Then I cut 4 pieces of N scale flex track for the rails on the existing deck.  These rails actually are the tops of the torpedo tube alley structure for loading the deck torpedo launcher.  They used a small four wheel trolly to bring the torpedoes forward to the loading gantry.
If you squint real good you may be able to see the four hatch doors for the loading tube well next to the well opening.
 

This shows the mounting block for the stern loading tube.  
 
Cheers,
 
 

Thank you, druxey, Christian and Ed. All of this re-posting is allowing us to see all of the builds afresh! Ed, I will be particularly happy when we have your index again. I used that fairly regularly.
 
Daniel, the blue track idea comes from Ed, and it is made from components purchased at Rockler Woodworking. All of the parts for the track and the tightening bolts and knobs are already made. The link to the site is:
 
http://woodworking.rockler.com/c/jigs-jig-its-t-tracks
 
I recall that I used a router with a bit exactly the width of the track, using a fence on the router to keep it parallel to the sides of the building board. Once the grooves are cut, the tracks are very easy to screw in.
 
The bridge was a little trickier, because it wants to be exactly right angles to the building board, and have some way of lining up with the station lines of the plan on the board. Ed developed one idea, and I tried a slight variation that I showed in the previous pictures. Ed, are you able yet in your re-posting to link to your bridge design?  I recall Ed has an way of fixing his camera to the bridge, which I want to try someday.
 
The final complexity was to get the top of the bridge to the building board surface to be exactly the same distance as the top of my board with the section drawing pasted on, to the bottom of the keel. That is so measurements taken off the board with the drawing will exactly match the same height on the actual model measured from the bridge. I hope the photos explain this well. If not, I'll do a little drawing of the arrangement.
 
Best wishes,
 
Mark

JIG QUESTION.
 
Good Morning Mark!


Now that we´re all re-starting the logs can I ask you to explain how you built the second Jig.
 
The one made like Ed did.
 
If you could make a sketch on paper it would be fine. I am wondering about theclamps inside that blue aluminum rail. The bridge is a great to meassure distances, deck beams, gun ports...


Thanks.