30ft 1890's navy steam launch 1/6th scale

Quote from: tghsthe ash was used as trim alternating with cherry,, it more importantly was used in the seating slats that were bent to follow the curve of the stern.. most of my 30ftr files are to large to post but some 40ftr info give you the idea,, all of the "trim" wood would have been kept in a good coat of waxed varnish..

The use of ash wood for trim and seating slats seems very sensible. Ash will steam bend easily and provide flexibility for the curved seating slats. It's a trim wood, not structural, and would be relatively easy to replace when necessary.

The last photo looks just like the inside of Boathouse #4 (small craft) at Portsmouth Dockyard here in the UK

Mike

Looks like Alex's boat.

Quote from: VixenI'm No boat builder so I may have this totally wrong. I am surprised at the use of ash wood on a boat, I have only used ash wood to build the frames for vintage car bodies, the wood frames were covered with either metal sheet skins or fabric. The ash frames were  used because ash was a light flexible wood, but it tended to wet rot after a few years due to the effect of rain water etc. So you can see my surprise at it being used in a marine environment. Hope you find a suitable replacement.

Mike

Ash does get used a lot in boats, fine as long as it is kept painted or varnished - it will soak up water very easily if left bare. It is great for bent parts, just soaking in water overnight will make it very flexible (does have to be straight grained to take a tight bend or it will crack along the grain). I've used it myself for ribs in small boats for decades, never had any rot issues.

Quote from: cruebyAsh does get used a lot in boats, fine as long as it is kept painted or varnished - it will soak up water very easily if left bare.

That's interesting. The ash frames of vintage vehicle bodies are generally left in the bare, un-painted/varnished condition. It's the ends and the joints which usually rot out first.
Sounds like vehicle restorers are missing a trick. However, vintage vehicles have become so valuable that they are rarely left out in the wet any more, so the rot problem no longer exists..

Mike.

getting back to the nuts and bolts, hopefully I can get to work on the crankshaft this week as I'm still deciding on how to build the connecting rod bottom ends , either using 2 bolts as per Stuart Turner or the strap with wedges as in the prototype..

Very interesting drawing - the piston heads look to be conical shapes rather than flat, do you know why they are that way??

If you're going to run it hard ....I'd probably go the Stuart route, but considering the level of detail that your working to, I think you need to do the strap. ....don't forget the box links...very important.

Dave

thinking of taking a good try at the navy type bottom ends (I have spare rod castings on hand) looks like navy idea was for quick in place bearing replacement, knock the wedges out-drop the "strap"- swap out the bearing blocks- "strap" up and wedge.. as it may not look as positive compared to nuts and bolts most likely held well.. and I will have the benefit of loc-tite type products..  been looking at the box type links and thinking that they offer me the "chance" to get a small rotary table for my mill.
  The cone cylinder head, piston and bottom, thinking the navy engineers moved the shaft gland unit "up" into the cylinder,, making for shorter frames and maybe block.. the US Navy at this time was a driving force in developing tech of the day.. one area was in advancing foundry work  (many castings most likely were more complicated than needed) the creation of the navy ordnance dept, so that no guns would be of foreign production..the "harvey" steel armour  process was developed with navy funding..

Quote from: tghsthinking of taking a good try at the navy type bottom ends (I have spare rod castings on hand) looks like navy idea was for quick in place bearing replacement, knock the wedges out-drop the "strap"- swap out the bearing blocks- "strap" up and wedge.. as it may not look as positive compared to nuts and bolts most likely held well.. and I will have the benefit of loc-tite type products..  been looking at the box type links and thinking that they offer me the "chance" to get a small rotary table for my mill.
  The cone cylinder head, piston and bottom, thinking the navy engineers moved the shaft gland unit "up" into the cylinder,, making for shorter frames and maybe block.. the US Navy at this time was a driving force in developing tech of the day.. one area was in advancing foundry work  (many castings most likely were more complicated than needed) the creation of the navy ordnance dept, so that no guns would be of foreign production..the "harvey" steel armour  process was developed with navy funding..

The conical pistons were easier to cast and stronger, and as you said, made the engine a bit shorter and reduced weight and clearance volume.  A conical piston for a given thickness was stronger than a flat piston.  It was also easier to push condensate out of the cylinder with a conical piston than a flat piston.    The bearing straps allowed the engineers to keep their bearings tight without having to take a bearing cap off to remove a shim.    I'm sure keeping the engines silent was a good way to impress a senior officer, and likewise garnering a lot of attention if they knocked.  Reportedly, it was found that engineers were filing the slots in the links to get longer cut-offs, so they changed the links to box links, which beat that problem.

did some milling and turning to look at if the the navy strap and wedges will scale down by 6,, looks like the area for the wedge slot has enough material to work, this will cause some redesign from the castings and a soldering operation.. need to order up some brass and bronze but I have a list of other needs for the boat,, lots of other stuff to work on other boat and engine parts..

I'd cut that from a much larger piece and from the center of that piece to keep it supported.  A few well placed holes to locate the bend radii, and you can machine the whole part complete and ready to slide on.  The square slots are the tough bits I think....I would make the keys first,  Mill the slots, and finish with a file or a die filer....of course if you happen to have a wire edm...well..

The LAST thing would be cutting the strap from the mother material....well  that's how I would do it anyway....

Watching along.

Dave

have done some more design work and ordered up some materials,, thinking they will look close to the prototype,, planning a built up crankshaft, loc-tite 603 and pins,, the webs have been machined  and just need drilling-reaming,, thinking that the connecting rod shaft sections (5/16ths shaft) could be centered drilled,, small cross shaft holes added,, the idea being that it would work as oiling points for the bottom ends,,plugs could be added to the shaft ends (one with small oil hole) making the work like reservoirs,, thoughs  ?

forgot that I did make a wedge lock system a few years back (just a bit larger) did some drawing on the oil idea, as for navy late 1800's casting, photo shows a modern attempt to replicate the condensate pump.. that's not going to scale, have a simpler type in mind that will look correct from the outside..

Quote from: tghshave done some more design work and ordered up some materials,, thinking they will look close to the prototype,, planning a built up crankshaft, loc-tite 603 and pins,, the webs have been machined  and just need drilling-reaming,, thinking that the connecting rod shaft sections (5/16ths shaft) could be centered drilled,, small cross shaft holes added,, the idea being that it would work as oiling points for the bottom ends,,plugs could be added to the shaft ends (one with small oil hole) making the work like reservoirs,, thoughs  ?

I'm looking for an illustration I saw some years ago for the lubrication technique used on the TBD boats with 4 legged triples.    They had this "pie tin" slinger on the side of the crank cheek that oil dripped into near the main, and centrifugal force would bring it out to the big end bearing....If I find it I'll post it....half the problem is remembering where I saw it 

Dave

This is the concept.