Roman Quadrireme Galley by Ian_Grant - 1/32 Scale - RADIO

[Ian_Grant]

"SEA TRIAL #1"  !!!!!

 

Tweaked the software to map the servo signal pulses to appropriate limits and polarities to suit the actual physical setup. For example, the two sweep servos drive their associated mechanisms using opposite ends of their arms, so giving the same PCM signal to both would drive the oars in opposite directions. One pulse stream has to be "inverted" i.e. pulse width is "reflected" about the 1500 usec midpoint e.g. if one servo is at 1700usec (1500 + 200), the other has to be at 1300usec (1500 - 200) which results in both sweeps moving the same way. This is very easy to do using the Arduino "map" command.

 

I made up little "sacks" for lead shot ballast using cut up envelopes wrapped in packing tape. They fit nicely in the hull bottom between the bulkheads. At our new pool, it became obvious that the bow is much more buoyant than the stern, so bow needs more ballast. There is an awful lot of ballast...an awful lot...haven't weighed it but it is many pounds. My hull weight estimate was far too high, my resulting u/w hull has far too much bilge. In the videos below, you can see that moving forward and back is pretty slow since all that dead weight must be moved; but with oars stroking in opposite directions it turns in place not too badly, since the weight is not having to be actually moved along. Question is whether she will move better with more oars of the same blade size.

 

As mentioned in the video, the next step is to rubber-band larger oar blades on to try to predict the effect of 42 more oars in the second tier. I am thinking of making new partial oars with a bigger blade, then cutting the existing oars and scarfing the new ends on. This would be easier than trying to cut out exactly the old blade notches to add new blades.

 

I also conclude that a central handle is absotively a requirement. Hefting this thing around is a chore even without the second tier of oars sticking out even further.

 

Evidently she will not be finished this year. That being the case, I am wondering if over the winter I could cut out the bilge curves and form a new u/w hull with less volume (😒) thus less ballast required and more responsive operation. Very painful sounding especially as the u/w hull is epoxy-resined inside and out. Will have to mull it over given results of the next trial.

 

Here's the first video:

 

 

Then I realized I forgot to demonstrate the effect of opposite stroking. As a refresher, when software sees a "hard over" rudder signal, as currently written, it reverses the oars on the inside of the turn. Obviously she has no rudders, or indeed steering platforms, yet, but the software still reads the signal indicting position of my transmitter's rudder stick. Looking back, I think she spun to port when I "applied" hard-right rudder and vice-versa. That's a matter of more simple software tweaks in the unknowable future.

 

Here's the "spinning" video:

 

 

Edited August 30, 2023 by Ian_Grant

[BobG]

Wow...that's amazing!

[gjdale]

Amazing work Ian. Congratulations on achieving a successful first sea trial. I wonder if you really need to increase the oar blade size though - with an extra bank of oars, would the speed actually look about right for the scale?

[Bedford]

I was thinking the same as Grant, once you get the second tier of oars it should speed up, yes it's slow off the mark but then it should be.

Before worrying about oar size I'd suggest you work out the theoretical hull speed "Hull speed can be expressed as a simple mathematical formula 1.34 X the square root of the length of the waterline (HS = 1.34 x √LWL). For instance, if a cruising sailboat has a waterline length of 36 feet, she should be able to sail 1.34 x 6, or approximately eight knots." 

Then work out the scale speed of the boat and take it from there, mind you it's doubtful such a big rowing boat would have ever attained hull speed.

 

As for the amount of ballast, I'd leave that as is too for now because water doesn't behave in a scale fashion so if you make it lighter it might get tossed around like a cork. The ballast helps her ride in a more scale manner. 

[Glen McGuire]

That is absolutely amazing work, Ian!  Congrats on a successful test run.

 

In the first video when you said, "Something's gone wrong" all I could think of was "Houston, we have a problem."  But you get her fixed and cruising across the water.  Awesome!!  

[Ian_Grant]

21 hours ago, gjdale said:

Amazing work Ian. Congratulations on achieving a successful first sea trial. I wonder if you really need to increase the oar blade size though - with an extra bank of oars, would the speed actually look about right for the scale?

You may be right ..... another trial with extra blade area rubber-banded on should give an indication, although I must say the blades look teeny when you view them against the large hull.

 

Thank you for following thus far, and your good comments!

 

20 hours ago, Bedford said:

I was thinking the same as Grant, once you get the second tier of oars it should speed up, yes it's slow off the mark but then it should be.

Before worrying about oar size I'd suggest you work out the theoretical hull speed "Hull speed can be expressed as a simple mathematical formula 1.34 X the square root of the length of the waterline (HS = 1.34 x √LWL). For instance, if a cruising sailboat has a waterline length of 36 feet, she should be able to sail 1.34 x 6, or approximately eight knots." 

Then work out the scale speed of the boat and take it from there, mind you it's doubtful such a big rowing boat would have ever attained hull speed.

 

As for the amount of ballast, I'd leave that as is too for now because water doesn't behave in a scale fashion so if you make it lighter it might get tossed around like a cork. The ballast helps her ride in a more scale manner. 

Looks like it's time for some more math .... 🫢.  Thanks for following from the beginning!

 

15 hours ago, Glen McGuire said:

That is absolutely amazing work, Ian!  Congrats on a successful test run.

 

In the first video when you said, "Something's gone wrong" all I could think of was "Houston, we have a problem."  But you get her fixed and cruising across the water.  Awesome!!  

 

HaHa!  Thanks Glen. I really don't know what happened which is worrying. Is the 2-year old battery feeling the strain? Did the Arduino burp? Battery cable too long? Needs investigation.

Edited August 31, 2023 by Ian_Grant
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[BANYAN]

That's incredible work Ian; that appears to be a very effective mechanism.

 

cheers

 

Pat

[Ian_Grant]

1 hour ago, BANYAN said:

That's incredible work Ian; that appears to be a very effective mechanism.

 

cheers

 

Pat

Thanks Pat!  Another challenge will be adding steering platforms and twin rudders controlled by a servo linkage through the hull sides, beneath the platforms. I already have the hardware parts. Need to determine suitable size for rudders.

 

Thinking of using the library's laser etch/cut machine to etch the deck planking on the steering platforms, and if successful on the main deck and even the tops of the outriggers.

[Bedford]

On the subject of rudders, I wonder if they were, in reality, more trim tabs than actual rudders, as is the case in tall ships in which the set of the sails does most of the heading work.

 

Having had the helm on a 4 man row boat I can tell you the rudder only has any real effect when the oars are out of the water so you end up with a segmented turn.

[Jack-in-the-Blue]

What a fabulous project!
 

The sound of the motors perhaps simulates the wheezing breath of the oarsmen. 😁

[Hubac's Historian]

Fabulous progress, Ian.  It is nice to hear your  voice in the videos.

Edited August 31, 2023 by Hubac's Historian

[Ian_Grant]

5 hours ago, Bedford said:

On the subject of rudders, I wonder if they were, in reality, more trim tabs than actual rudders, as is the case in tall ships in which the set of the sails does most of the heading work.

 

Having had the helm on a 4 man row boat I can tell you the rudder only has any real effect when the oars are out of the water so you end up with a segmented turn.

I suppose they could have told oarsmen on one side or the other to "ease up" in order to steer, who knows now? My plan was to use rudders for slight/gradual course changes and leave the counter-stroking as an ace up the sleeve; I'm not sure they could even do that in reality. One gets far less power pushing an oar than pulling it.....

 

During our week's cruise aboard "Royal Clipper" a 5-mast square rigger I had the opportunity to steer her one evening. What a rush! Five thousand tons under my helm control. If she was drifting off course, and you moved the rudder, her inertia slowed her response dramatically but once she was turning that same inertia made it hard to stop......took some getting used to anticipating it ....

4 hours ago, Jack-in-the-Blue said:

What a fabulous project!
 

The sound of the motors perhaps simulates the wheezing breath of the oarsmen. 😁

Yeah, the servos are noisy. I'm hoping the full deck will muffle them.

 

1 hour ago, Hubac's Historian said:

Fabulous progress, Ian.  It is mice to hear your  voice in the videos.

Thank you Mark!  I only wish I could stop the stammer which only started in my late 20's for some reason.

I'm looking forward to adding the steering platforms and decorative trim, and painting of course....

[Hubac's Historian]

I had not noticed, Ian.  I will say, though, that it is our quirks that endear us to each other.

[Ian_Grant]

SEA TRIAL #2 !!!!!

 

While getting set up for this trial, I noticed my supply to the Arduino was intermittent (thank God for the power indicator LED on the board). Without a USB connection from a laptop, the Arduino gets its power from a 9V battery connected via a jack and the Arduino regulates it down to 5V. Two issues: (1) my 9V battery was giving barely 6.5V so the regulator was close to not being able to work (needs a certain amount of ceiling above 5V at its input), and (2) I forgot to solder one of the connections in the jack (!). So that's why the problem in Trial #1.

 

This time I simulated the second tier of oars by adding suitably sized slices of pine to the existing oars' blades with rubber bands. I am delighted with the result, she moves much better. I now look forward to making and adding the second tier of oars, finishing up the hull, adding the removable deck, and painting her.

 

Here's a video of this trial. I remembered this time to try out the various turning features i.e. inside oars stopped, inside oars reversed, depending on how sharply rudder is turned.

 

 

Edited September 2, 2023 by Ian_Grant

[BANYAN]

Impressive!  

 

cheers

 

Pat

[Ian_Grant]

Started production on 42 upper tier oars plus spares. I decided I wanted the blades 1/8" wider and 1/8" longer for good measure. Thinking about modifying the existing oars, I decided it would be easiest to trim their edges back to flat then add u-shaped additional wood, rather than messing around with the glued shaft/blade joints or scarfing new ends on. Further it would add some pizzazz to make the additional wood a contrast to the cherry ie use maple.

 

Given all this I decided to make the upper oars with the wood contrast too, only in reverse to add yet more pizzazz.

The shafts are 1/2" longer to decrease overlap between the blades from the two tiers.

 

Here we have the notched shafts and the formed blades. Making oars - deja vu all over again....

[Ian_Grant]

Well I have all 42 upper oars made and varnished, and 21 of them mounted on the port side. It's looking good ..... but .... when I added 1/2" to the upper oar shaft length in order for their blades to lie beyond those of the lower oars, I inadvertently created a problem. The oar ports have to be elongated to allow the shafts to sweep and I mentioned way back there is some play. When I row the oars just on the bench, sometimes a few of the lower blades cross under an adjacent upper shaft at some point in the cycle then there is a clicking noise as they clash and are corrected. The real solution is to redo the loom ends of the upper oars, removing the extra 1/2" so there is some blade overlap which should stop the lower blades from crossing under.

 

Or perhaps it will be ok when they are all in actual water ..... will do the starboard side then have Sea Trial #3. Soon I hope.

 

Here are a couple of pics. I changed the mechanism design to use just three hex metal standoffs to support the pivoting beam for the upper oars, as opposed to the solid wood with drilled holes I had before. The holes were intended to provide access to the mounting screws for the lower oars but it was too difficult to get to the screws in, without dropping a lot of them into the bilge, when adding the oars. As can be seen in the 2nd pic the access now is much better. See the increased size of the blades of the upper oars. They look lighter than the lower blades because they're freshly cut cherry; over time they will darken as the older blades have done.

 

Edited September 14, 2023 by Ian_Grant

[BANYAN]

Love your process and determination to get this right Ian; an interesting log to follow.

 

cheers

 

Pat

[smileyjon]

Quality build . . . I'll never build one but I'm following this  !

[rookie]

nicely done Ian.

I like the new pool too 

[Ian_Grant]

Added the upper pivoting oar bar to the starboard oar beam. She can now be seen in all her glory as an 86-oared vessel! Since I'm now using all the oar ports I fished the lamp cord I'm using for the battery connection through the bilges using the holes I had made in the bulkheads.

 

Too late today for a sea trial. In any case I ran into more 9V problems. I had bought a 4-pack of 9V snap connectors with pigtail leads from our local electronic components store. So far I've had occasion to unplug a 9V battery twice; both times the negative terminal on the connector, instead of unplugging from the battery terminal, tore through the connector's flimsy plastic. What a bunch of made-in-China crap! Opening it up I found the connector terminal has almost no flange inside - how do they expect it to pull out of the tight battery terminals?  😠

So once again I'll need to re-solder the jack onto another connector for the purposes of the next trial.

 

What to do next? I can find all kinds of these things, some as cheap as 65 cents (who can source parts, make the product, ship it, and have it sold at retail for 65 cents?). No one with any quality product. 😒  I want to see and handle any replacement candidate before buying but there's nothing else local. I'll even consider getting one of those little boxes that holds six AAA batteries, if I have the space.

Hoping to trial her tomorrow, if my son is around to shoot a video.

Edited September 19, 2023 by Ian_Grant

[Bedford]

All that beautifully intricate work foiled by cheap crap auxiliary components. It drives me mad that I can't buy good quality things like that anymore

[smileyjon]

I can get them for £1 each and they are described as heavy duty ones with 150mm 'tails'

[Ian_Grant]

Thanks, but they don't look heavy-duty to me, almost as thin as mine. I DID find some very sturdy 9v-connector-to-5mm-jack adapters in a music store, used to power up guitar pedals apparently. They were American made, thick and solid because a band can't afford to have them fall apart. I had a 9V battery with me and loved the solid feel of plugging and unplugging and I thought I had it solved. Unfortunately the standard in the music industry is that the jack is tip-negative whereas any Arduino is tip-positive in keeping with the electronics industry. I could buy one and cut the wires up but it's just one more joint to fail.

 

I ordered a thick-looking part on Amazon, made by "Pacific Science Supply", so we'll see how it is when it arrives.

Edited September 22, 2023 by Ian_Grant

[Ian_Grant]

A day to remember - Sea Trial #3 with all 86 oars!!

 

My conclusions from this trial:

 

1)  The upper oar blades hang lower than my geometry drawing, which is ok for power stroke but they nearly drag on the water during return stroke. Any slight ripple on the water will be a bother. Checking on the bench again, they do seem to be about 1/4" lower than planned. Will need to revisit the upper oar bars this winter and mount them again more carefully. Probably would be a good idea to change their mounting holes in the beam to vertical slots to allow adjustments on the fly. Would need to, I guess, find a 5/32" milling bit and use my drill press and some jigs. It probably doesn't help that I made those oars 1/2" longer....thinking I will take the extra length off, and make the lower oar blades the same slightly larger size, over the winter.

 

2)  She is very sensitive to ballast amount and distribution, surprising me given her size and full, rounded bilge. Will need to adjust the whole ballast scheme when model is complete and final weight is known.

 

3)  Realistically proportioned rudders have very little effect; there's no prop wash to apply force to them. I don't want hugely exaggerated rudders on the model so I'm wondering whether to even bother having them servo-controlled! Also, now considering rewriting the software, over the winter, to have the inside oars on a turn go to a shorter stroke, still in time with the outer oars as far as power/return goes. This would make her turn for sure. As rudder moves over more the inside stroke could get even shorter, at some point simply stopping out of the water, and going to reverse stroke at rudder hard over. Haven't thought about code but this sounds pretty complex to me since there would be different "delta-X" increments for the two sweep oars; plus we already have the new requirement of varying the sweep servo rotation rate to try to maintain a constant sweep velocity, as mentioned in a previous post.

 

4)  She's damn heavy and awkward to carry through doorways.  My initial scheme of having a central handle is an EPIC FAIL. 😭 You know that exercise where you have a dumb-bell in your hand and lift your arm straight out to the side .... that's what it would be like since you must keep the oars clear of your hip. 🙄  I'm now considering a very solidly built handle across the hull very near the stern, beneath the front edge of the fixed portion of the aft deck. One would grasp this and lift up stern first, then place other hand under the hull at mid-keel and carry it like a golf bag for example. Will be an interesting winter.

 

With all that, here is the video. Thanks to all for following me thus far!!!

 

 

Edited September 22, 2023 by Ian_Grant

[BANYAN]

Coming along well despite the set-backs Ian.  An interesting video.

 

One small point, while I am unfamiliar with this period of history, many oar steered vessels only used a single oar at a time.  Were these vessels using two?  Perhaps a trial with a single oar may offer different effect?

 

cheers

 

Pat

[Thukydides]

This is awesome. Great job.

[Ian_Grant]

11 hours ago, BANYAN said:

Coming along well despite the set-backs Ian.  An interesting video.

 

One small point, while I am unfamiliar with this period of history, many oar steered vessels only used a single oar at a time.  Were these vessels using two?  Perhaps a trial with a single oar may offer different effect?

 

cheers

 

Pat

Hi Pat;  my Conway book of galleys has reproductions of ancient drawings showing Egyptian, Phoenician, and Hellenic galleys with twin steering oars. The trireme "Olympias", launched around 1990, had twins which were very effective as shown in videos available on youtube.

 

My Pitassi book on Roman galleys also shows them with twin steering oars, as gleaned from surviving stone relief carvings and even wall paintings uncovered in Pompeii. There's a place on my bucket list!

 

I realized that in the video, or maybe after it was shot, I had it rowing with oars on one side stopped (out of water) and it didn't turn much even then so my plan of shortening the inside stroke probably won't work. Maybe I'll have to put exaggeratedly large rudders on her after all. It will look awkward if I have to keep doing reverse strokes to steer.

Edited September 22, 2023 by Ian_Grant

[gjdale]

Despite some obstacles to overcome Ian, this is still very cool!!!

[Glen McGuire]

Amazing work, Ian!!!  This has been fascinating to follow!