Ian_Grant

Yes she still floats. I cleaned off years of accumulated dust for the picture. I got to thinking it might be fun to run her again, same decaperm motors but with modern battery and brushed ESC's instead of the old rheostatic speed controllers I used to use in her. Well do I remember cleaning the contact area so the copper wiper arm could touch the coils of the partially-uncovered wire-wound resistor element in the rheostats.... no one under 50 knows what I'm talking about... Haha 😃. I think I will consider refurbishing her and taking her to the cottage for the calm evenings. Providing that the other decaperm is in fact in one of my other boats. I even thought it might be nice to pull the drawings out of the tube in the basement and add some more details. Her decks look pretty bare compared to some I've seen on MSW with hatches and scuttles all over. Probably I had trouble reading the drawings back then. LATER EDIT: I pulled out the drawings and wow, did I ever skip a lot of detail. Her decks are indeed full of hatches, ventilators, and scuttles. Also omitted all the light armament, armour belt edges on hull, protrusions on turrets which I assume are rangefinding lenses (?), vent pipes at the stacks, the frames at the top of the stacks (for covers when laid up in port?), all the doors, many many boats, etc etc. ill consider fixing her up but life is short; I still want to do this galley first.

Finally, after all these months, some actual numbers! Borrowed a fish scale from a neighbour. Testing in my (as yet unopened) pool, it reads about one lb pull when moving the twenty looms in a two inch stroke over one second. That's with blades measuring 5/8" x 1-3/4", and a loom length of two inches which is my desired value given the boat's likely beam. I can extrapolate from there. Force will vary in proportion with blade area, and as the square of the stroke velocity (as I can attest from many many hours pedaling a bike into the wind!). Stroke isn't going to be faster than one second, and will be slower most of the time meaning much less torque (inverse of the square). Each sweep servo will power two remes of oars, so 2 lbs thrust needed. If the servo only moves 60 degrees it will need a 2" arm to give the 2" stroke which represents a torque of 4 lb-in. If it can move 120 degrees then a 1.15" arm will give the 2" stroke, representing a torque of 2.3 lb-in. Obviously a higher-rotation servo is desirable. Since fastest realistic stroke is about 1 second, servo speed is not likely to be a concern. In an earlier video I showed return stroke speed at 1.5 times the power stroke speed which looked pretty good. If I stick to this value then the oars will be in a power stroke 60% of the time, and a return stroke 40% of the time. Sweep torque will be essentially zero during the return stroke. Sweep torque during the power stroke will vary depending on the angle of the servo arm , but let's just assume it is a constant 4 lb-in (to take the smaller-rotation servo case above) to be conservative. Over a cycle, then, the RMS torque will be about 3.1 lb-in (if I calculated that correctly). This value is the equivalent continuous torque. Since I can't get any info on continuous torque from Hitec, I'll need to do some temperature testing at this torque, with the servo arm going back and forth with an appropriate weight on it. If I find a servo that does 120 degrees, then the 2.3 lb-in power stroke torque yields an RMS torque of just 1.8 lb-in. Now I can look through servo specs and make an intelligent choice. I have been unable to pry any info from Hitec regarding continuous torque specs or thermal limitations so I will just have to select a servo whose max torque, "heavily" de-rated, is likely to indicate a continuous torque rating exceeding the above RMS values. So, rookie, your head must really be spinning now! 😃 It's OK everyone, I can tease rookie......he's my brother! Other unknown is what force is required to propel the actual boat? I just happen to have a WW I battle-cruiser I built for RC in high school which has a length, beam, and draft very similar to the proposed galley. I used the fish scale to pull it on the water. From a standing start it needs less than one lb to get going, which is much less than its displacement. Since four remes of oars should provide in the region of 4 lbs thrust, I think maybe I'm making a dragster! 😀 LATER EDIT: I forgot to take into account the oar gearing. For the twenty oars collectively, the 1 lb pull from the servo at the looms yields 0.35 lb at the centroids of the blades. Four remes thus provide 1.4 lbs thrust against the water, far short of the 4 lbs I mentioned above. Here are some pics of the battle-cruiser beside the oars at the proposed scale (fish scale is also seen). Size looks about right! The ship is Admiral Beatty's flagship HMS Lion, which was heavily damaged at Jutland. I got the plans from David MacGregor in the UK. Not a completely detailed build but pretty good for a teenager in the 70's. Powered by twin Decaperm motors (lovely motors, one of which remains) and oversized propellers which pushed it along like a destroyer. The other motor must be in one of my other old RC boats. There's even an old servo in there; might be fun to try it out.

Looking great!

Bill, if you get down there you must see Zion National park. It's like nothing we had ever seen, even though we just drove through it on a loop from Vegas. Promised ourselves to hike there someday. Sorry to digress from the ship, Tom! You seem to be a fast worker like Bill; he has nearly done the standing rigging after 11 months whereas most people take years to build this. Took me five. 😀

That would be ideal. My brother has a PLA printer; not sure I could drill and tap PLA without it cracking. Maybe I could prototype it in PLA, finalize it, then get my local machine shop to CNC eighty out of aluminum for me, including a tapped hole for a grub screw. Now that would be awesome! In fact, I can cut aluminum with my tablesaw/router using carbide teeth/bits. I'm sure I could jig up something to drill the holes repeatably....Thanks mtaylor!

Well no, that only occurred to me after; the 1/3 came to mind from 18th century ships. I expect wire, being stronger for a similar strain, will be smaller than a rope shroud so the lanyards will be a bigger ratio. I'm sure Longridge's Cutty Sark book must detail this, if it's anything like his book on Victory.

Yes, but the circumference and diameter vary in proportion. Longridge's "1/2 circumference" equates to "1/2 diameter" too. 😃

I built a jig to measure the force required from a sweep servo. It consists of 20 oars in a single tier as shown: The clamps at the ends allow adjustment of the "gunwale" position to change the ratio of the oar inboard loom length to total length i.e. the "gearing" of the oars. I just cut a flat on the ends of the oar shafts. Rubber bands hold the blades in place, allowing me to try different blade sizes. I slapped some "Helmsman" spar varnish on them. The plan now is to borrow/steal a spring fish scale and use it to pull the oar looms to measure the force. Still the cheap screw connections. For the actual ship I will use u-channel from Servocity to hold the oar ends. This channel is drilled at 8mm intervals. I will space oars every 5th hole, so 32mm apart. The upper tier will use the "3rd holes" in their beam to place them centred between oars in the lower tier. I was thinking of 3D printing a better oar attachment to allow them to pivot nicely in the u-channel. Something like this which I drew in TinkerCAD: The small hole is for an M4 machine screw which passes through the sides of the u-channel. The large hole is for the oar shaft to glue in. Disadvantage is that once glued in I cannot remove an oar from the boat, through the thole hole. I even contemplate making brass oars, then I can solder the blades in and solder a square tube at the inboard end; in this case the larger hole in the fitting would be square, obviously, and I can perhaps drill another hole to pin the shafts into the fitting and allow oar removal. The u-channels themselves will simply be hinged to the beam to allow them to tilt as the beam moves up and down. I have decided to use Servocity T-beam extrusions and mini v-rollers to mechanize the vertical movement, instead of round shafts and linear bearings. A bit cheaper, plus I can space the v-rollers at whatever distance whereas there are only two choices for length in linear bearings. That's all for now. Eager to see what kind of force is needed!

I think the simple rule of thumb is lanyards are 1/3 the size of the shroud or so. I see, though, that Longridge mentions 11" lower shrouds with 5-1/2" lanyards in the case of "Victory" at least; seems a bit overkill since the strain in the lanyard is divided by six....

Oh, I meant that the backstays were not done at all at the time I did the ratlines, but go ahead........

Couldn't recall what I did so I looked through my old pic files. I definitely did the ratlines with the topmast backstays just dangling, aft of the masts.

Bill, in the case of the lower mast head there are no backstays and the stay passes around the sum total of the clinched shrouds. As on your model. In the case of the topmast head, the stay similarly passes around the the sum total of the clinched backstays and shrouds. See Plan 9. The first photo is incorrect in having the stays buried under the backstays. Plan 9 has a nice inset drawing on sequence at mast head too. Finally, I notice in your pic that the mice are dark. You decided to paint the pearls?

I'd love to see some pics of these..................

For a moment there I thought you were going to try to rig the guns on the ship....Haha...now that would be a real miracle...

Agree with Daniel about the 5 sizes. For example, the 18" fore stay is not quite as large as the 19" main stay, but at scale 1.6mm is good for both. Same goes for blocks. Each available block size must cover a small range of actual block sizes.

In scale, the fore and main stays are 1.6mm, their preventers are 1.3mm. Fore and main topmast stays 0.75mm, preventers 0.5mm. Main and fore shrouds 1.0mm, topmast shrouds 0.5mm. Anchor cable was 27 inches in real life, which is 2mm at scale. Keep up the great work!

Kevin, I love the cat head on the cathead. Checking my old CS, there's nothing there, as you know. I would truly like to build another Revell CS and correct the deadeyes & lanyards at least, and rig proper shrouds, but I doubt there are enough years to get to it. 😢

Man, that's a lot of future work! The Heller Victory alone is a years-long effort for most.....happy modelling!

Bill, it might just be the camera angle, but it looks like your bunt lines are going through the double blocks below the sheave instead of above it, at least on the starboard side. The jeers and sling look good!

Bill, not sure what reference books you have. I don't have any simple diagrams. Longridge plans 8 and 9 are pretty good for all the blocks near the centres of lower and topsail yards. Also plan 7 "Running Rigging", although it takes getting used to, shows all the blocks mounted on yards and positions of footrope stirrups etc. But you need to know what you're looking at e.g. the two buntline blocks on a course vs the singles on a topsail yard. It takes some flipping between plan 7 and the other zoomed-in drawings. Sorry!

I tend to put on backstays and corresponding stays (ie at same level of mast) at the same time. That way you can tension them all and lock down the position of the mast at that level. Then move up to the next level.

The usual thing is to have small-value capacitors across the motor leads, and from each lead to motor case "ground", to suppress RF radiating from the motor. At least in the case of brushed motors.

Gee, I've been to Strasbourg twice but didn't know to go and see those cannons. Wife and kids wanted to see the astronomical clock mainly, which I had told them about from my first visit, as a bachelor on a bike trip. Your guns look fantastic!!

Brings to mind the Monty Python skit about the fellow contacting an advertising agency because he has "a quantity of string" to sell. He speaks to one of the partners, a Mr. Wapkaplet, about selling the string which amounts to 122,00 miles. Difficulty is that the entire quantity is in 4 inch lengths (I think it was 4, might have been 6). Mr. Wapkaplet goes on to brainstorm about how to frame the advertising campaign....... Gotta love Monty Python. But they'd never get away with the stuff they did, on TV these days............

Richard, thank you so much for the detailed data on the stroke! Fascinating to study. I can see I have a lot of coding to do especially in details of the lift motion. I just started building a jig with a reme of 20 oars; plan is to use some sort of strain gauge to measure sweep force required to move blades in water. This equates to rowing with no response from the ship ie no acceleration, which will give me the maximum possible force. I've been looking at the Hitec HS-755MG and HS-805MG giant analog servos, hoping the 755 will serve because the 805 draws half an amp just to move its arm with no load (!). But we'll see what falls out of this next test. I'd rather have a big motor loafing along than a smaller motor labouring, provided the big motor isn't too power hungry. As for the mechanism, I drew up some ideas using servocity structure and motion components. The vertical motion will definitely be linear bearings on 1/2" vertical shafts. My prototype oar attachments were crude, just a flathead screw left a little loose so the oar could tilt. I now plan to mount the oars in a u-channel which allows sweep movement only; the u-channel itself would have to pivot along its axis to allow the lift movement. I considered mounting shafts axially at the ends of the u-channel, said shafts passing through bearings mounted in pillow blocks, but that's a little pricey. The fallback is to simply mount the u-channel on hinges so it can tilt around as the beam moves vertically. Again, thanks for the useful data. I'll need to improve the code defining the stroke shape, for sure. By the way, there is a GPS "shield" for Arduino. Hmmmm....... https://www.robotshop.com/ca/en/sim28-arduino-gps-shield.html?gclid=EAIaIQobChMIlpWOlvS29wIVRCCtBh18uAqKEAQYAyABEgK3LPD_BwE