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

[Ian_Grant]

2 hours ago, Louie da fly said:

Do you have a picture of how you want it to look? You might like to have a look at how I did the one on my dromon.

 

She's looking very good.

 

Steven

Thanks Steven! Yours looks great but it's far beyond my artistic ability.

 

Not sure how I want it to look. Or what they had if anything. In Pitassi's book some of the larger ships have what looks like a permanent structure, like the quinquireme in this video ( see time 0:46). I think a quadrireme would require something lighter due to reduced size and number of oarsmen. Pitassi indeed shows nothing in the quadrireme drawing but has an arched tent-like item in other drawings.

 

 

Something more like what is shown in the ships here. Most have a "tent" of some sort with, thankfully, one plain colour or at the most stripes. That's a relief.

 

https://naval-encyclopedia.com/antique-ships/roman-ships

 

A snag is that I was planning to attach the cubby to the rear hatch to serve as a handle (similar to the boarding bridge and the forward hatch) so it can't actually be soft. Maybe a "soft-top" arch with hidden wood in the lower sides for my big clumsy hands to grip?

 

 

Edited June 7 by Ian_Grant

[Ian_Grant]

Those not into RC can ignore this post. 😉

 

A little good news......I noticed at the RC club's indoor pool meetings this winter that if six or seven other boats were in use, my old FM 75 MHz two-channel set picked up some noise from them and the servos occasionally twitched. I have a 2.4 GHz 6-channel transmitter too, with "DSM" printed on it, which I bought with an airplane years ago but I wasn't sure if it was an old obsolete DSM1 unit or a newer DSM2 unit. I took it to Great Hobbies today along with a battery and a servo to experiment. It did actually bind to a modern DSM2/DSMX Receiver so it must be a DSM2 Transmitter. I bought a nice new 6-channel Receiver so now I too have an interference-free 2.4 GHz link. Nice!

 

Six channels are not needed for the galley, but my square-rigged RC ship will definitely need more than two as on my old FM set.

[Louie da fly]

I've just been looking for contemporary representations of these awnings - they're a bit few and far between - most are modern interpretations. But Trajan's column has this:

and these

And these frescoes are from Pompeii:

 

Not quadriremes admittedly, but certainly war galleys. And though other forms of awning are perhaps not unknown, these arched ones seem very common. 

 

I agree that if you want to use the awning as a "handle" you need something fairly robust. I suppose it depends how robust you want it. I've had success with the technique I showed above, but it probably isn't strong enough for your purposes. Perhaps turn a hollow cylinder on a lathe and then cut it lengthwise to act as the arched part. Or use a hollow metal or plastic cylinder the same way. Adding the vertical sides so the top doesn't pull away from them as you lift might be a problem. But certainly, something solid with a fake fabric top looks to be the way to go. And perhaps a bentwood fake framework (as shown on the pictures above) as well. Again, I've had success bending wood in quite tight arcs - see post #217 at 

Hope this helps,

 

Steven

 

 

 

[Ian_Grant]

Steven, thank you!  Those Pompeii frescoes are in Pitassi's book but somehow the b/w reproduction is nowhere near as clear as that. I see they really did use red and blue! 😊

 

That "Naval Encyclopedia" similarly shows some very tall awnings reaching the fantail but I don't think I want one like that; too much windage and I want to leave open the possibility of a flickering LED lantern dangling from it. I did drill a hole and glue in a copper eye before attaching it to the stern.

 

We're thinking of booking a trip to Italy which definitely will include time at Pompeii/Herculaneum.

[Louie da fly]

Glad you liked the Pompeii pics.

 

Naturally, go with the awning you want to have. You don't have to make it hard on yourself. I'm interested in seeing how you solve the problem of making it, but I'm sure you'll succeed.

 

Italy is an amazing place, chockablock with history. I've only been to Torino (Turin) and Rome, but even with just those two I was blown away. But make sure you include Venice in your itinerary, and spend time in San Marco (Saint Mark's) basilica. Apart from anything else, the mosaics are out of this world! (My wife's been there - I am so jealous!)

 

Steven

 

PS: I'd love a good picture of this mosaic, but unfortunately they don't allow photography.

 

[Ian_Grant]

Off topic but to continue about Italy; we spent some time in Venice and Florence on our 8 week (!) Europe-wandering honeymoon before departing for Corfu. Venice was good (we still remember the tour at the Doge's Palace, walking up to our ankles in water in St Mark's square,  and the ornate bed in our room) but I liked Florence better, apart from all the scooters zooming around. My wife chuckled at the reverent look on my face when I saw Galileo's tomb. 🙂 We didn't get to spend any time in Rome but next time we will go there and again to Florence, and obviously around Amalfi & Naples to hike Vesuvius and see Pompeii. Plus some time relaxing in Northern Italy.

Edited June 8 by Ian_Grant

[Ian_Grant]

Here's what I've been working on........

 

Drew two patterns of shield motifs in CAD and 3D printed ten of each. Painted them up and attached to bulwarks.

Drew some cleats and cut them out from 1/8" plywood using the laser cutter.

Here are the cleat boards which will be inside the bulwarks to anchor the mast shrouds.

Haven't yet painted the cleats.

Lashing and halyard cleat at the mast foot. Recall that the part of the tabernacle lashed to the mast comes off with it.

Cleats at base of artemon for yard inhaul/outhaul.

While I had a laser cutter booking, I cut out two rudder blanks from 1/4" clear cast acrylic sheet.

The etched stripes are where I need to cut a notch for the brass rudder posts.

Idea is to paint a scale rudder blade and leave the oversized portions clear.

Started work on the commander's shelter. It will be the handle for the rear hatch, bolted to it.

Hoping that stretching fabric over it will show the "tentpole" arches.

One more pole to add, in its slots. It crossed my mind to 3D print the end arches and slotted sides, but then I

gave my head a shake; "How lazy am I getting?".  🙄 It would have taken a good while to print, too.

Long weekend at the cottage a week tomorrow. I plan to debut it to all the inlaws and some friends, most of whom don't know I've been building it. It just never came up, HaHa......I'm the only one interested in building models or in RC.......Hope to have some rigging done, definitely the rudders, and of course use the new battery pack.

 

 

Edited June 26 by Ian_Grant

[Glen McGuire]

Top notch work, Ian!

[BANYAN]

She's coming on splendidly Ian, looking great!  Some very neat lashing there, bodes well for your rigging to which I am ;looking forward to seeing.

 

cheers

 

Pat

[rookie]

Looking great!

have fun at the cottage 

 

[Ian_Grant]

Routered a slot in each rudder blank for the square brass rudder post. This is a square tube into which a round rod is soldered; this rod passes through a brass tube at the steering platforms. Here is one left and one right rudder, with two little cover plates to be glued on. I roughed up the acrylic to give the glue some hook.

Painted-on "scale" rudders and the linkages; they will be mounted with the cover plates on the inboard faces. I used "JB Weld" epoxy for the first time. Wow it really grabs stuff but it's a rather ugly dark grey when dry, not a worry here due to painting. I polished the acrylic cut edges down to 600 grit wet. We just pretend that the clear areas are not there. 🙂

Rudders mounted. By the way I clear-coated the hull paint in exterior UV satin finish. I could not find exterior in matt. I am thinking of applying an interior matt over that, above the waterline, and hoping that it will stick.

A short video of the rudder action.

 

Size comparison of the NiMH pack with the lantern battery. No contest.

Then re-assemble the mechanisms. The sliding bases:

The oar beams:

After adding the oars I need to do a ballast test in the pool before taking her to the cottage tomorrow. It's supposed to rain all day Saturday so I will have more time to tweak it. Didn't have time to do much rigging, sadly. I will take the laptop too in case any software changes are needed. Video from on lake to follow............🤙👍

 

Edited June 28 by Ian_Grant

[Javelin]

Gorgeous work Ian, such vessels have sparked my interest in shipping during my childhood.

Love your solution for the rudders, looks very convincing. 

Perhaps a coat of matt varnish would solve the satin issue? However I like the satin finish, nothing really wrong with it. 

[Keith Black]

 Incredible work, Ian.

 

 Regarding coating, I used Minwax Polyurethane satin and it's some pretty shiny stuff. I recently tried Minwax water based Polycrylic matte and it's has some sheen to it. I then tried the flat and it has a lot less sheen but still a tad shiny but not bad. I was working out of the can (Polycryclic dries quickly) and started forming a skim on top within 45 minutes of open can use..

 

 I've yet to test Polycrylic on top of Polyurethane to see if the two are compatible. 

[Glen McGuire]

Amazing work, Ian.  Can't wait to see the next video of it on the water!

[Ian_Grant]

3 hours ago, Keith Black said:

 Incredible work, Ian.

 

 Regarding coating, I used Minwax Polyurethane satin and it's some pretty shiny stuff. I recently tried Minwax water based Polycrylic matte and it's has some sheen to it. I then tried the flat and it has a lot less sheen but still a tad shiny but not bad. I was working out of the can (Polycryclic dries quickly) and started forming a skim on top within 45 minutes of open can use..

 

 I've yet to test Polycrylic on top of Polyurethane to see if the two are compatible. 

Thanks Keith. Hadn't heard of polycrylic before. Will read up on it and see if it's suitable outdoors by chance.

[Ian_Grant]

Well, the test voyage at the cottage was underwhelming, so much so that I came home discouraged and didn't touch it for over a week.

She was unable to overcome even a slight evening breeze, moving backwards while rowing into it, and worse, the rudders had negligible effect.

 

I have thought of some avenues to explore.

 

To help the driving force:

(1) Increase the blade area of the (smaller) lower oars. I'm going to make them even larger than the upper oars.

(2) Simple software change to allow more strokes per minute.

(3) Simple software change to increase speed of return stroke thus spending less time not in water.

(4) More complex software change which I mentioned before but hadn't yet implemented: current software maintains a constant servo arm rotation speed which results in less horizontal movement of the oar blade as servo arm angle increases. Result is that oar blades move slower at the start and end of the stroke than in the middle. Need to modify code to maintain constant blade speed i.e. speed up servo arm rotation as arm angle increases. Should be fairly simple trig.

 

As for the rudders:

 

At the slow speed of the galley, they don't really generate much force unlike a rudder which is deflecting prop wash. I look at the situation and imagine the rudders trying to turn this long hull which is being propelled by oars spanning about 22" in total width.

 

My only idea at present is to add a skeg amidships on the keel to act as a fulcrum around which the rudder leverage might be able to act. This is a must: if I keep having to backstroke on one side or the other (which stops the ship in its tracks while it pivots around its centre point) every few seconds I will consider this build a huge fail. There has been so much rain lately I haven't had a chance to clamp on a temporary skeg for a pool test. Fingers crossed.

 

In the meantime I finally added the bow eyes and did some rigging.

 

I drew eyes in several sizes and colours in Inkscape (actually I drew a single eye then scaled and/or mirrored, and edited colour to get all the rest). I considered printing them onto wet-slide decal paper, or even my wife's label paper, but in the end I simply printed onto standard paper and used "Mod Podge" to glue them on to the ship. This was after testing eyes on some scrap wood to ensure colours wouldn't flow when I brushed acrylic clear coat onto them.

And the selected reddish eyes on the ship (not clear coated as yet, waiting for Mod Podge to dry).

Some mainyard rigging including halyard, lifts, and dangling dark brown shrouds, nothing tied off.

Sorry for the focus.

Parral.

 

 

Edited July 12 by Ian_Grant

[Glen McGuire]

Dang, Ian.  Sorry to hear the test on the lake did not go as planned.  However, I am confident you will figure out what adjustments to make.  

 

The eyes are a nice touch!

[Javelin]

Very sorry to hear that Ian. Not unexpected though, normal rudders on ships also hardly work when the propeller is stopped, regardless of the speed the vessel is making.

The skeg idea is unlikely yo work though. Ships rotate around their pivot point, which, at full forward motion, lays around 2/3 forward of the stern. It is the point that makes a circle in the water, yet the vessel rotates around it.

When stopped, that point moves to the center, when moving astern, the pivot point moves astern of the center. So moving forward, the rudders have a very good mechanical moment/arm to rotate the vessel (but bow thrusters are limited in effeciency to a speed where they become truly useless). When moving astern, a rudder is almost useless, but a bow thruster gains in efficiency. 

Adding a skeg midship is not going to change the behavior of the pivot point.

I believe enlarging (clip-on perhaps) the rudder surfaces or angle might be more beneficial. 

Regardless if everything is on scale, unfortunately "water" does not behave on scale (Froude number et.). That's also the main reason manned models for navigation courses are in scale, but prop and rudder are way out of scale to get to a realistic manoeuvering characteristic. 

 

This is not to discourage you and if you can test the skeg in an easy way, I'd be happy to be proven wrong. I just don't want you to have too high expectations of that solution and encourage you to think of plan B and C to get this to work. 

 

She does look awesome after all! 

 

[Richard Braithwaite]

As for model rowing boats performance, you do have to modify your expectations based on the scale effects. Different aspects of the boats performance will scale differently. One critical aspect is that if you operate the vessel with an appropriate stroke rate (e.g. 45 strokes per minute) the maximum speed  can never be more than the speed of the oar blades relative to the boat. This should actually look quite realistic (e.g. the model will travel at a speed roughly equal to full size speed  multiplied by the scale factor), but the speed will be far to low for the hull to behave as full size (e.g. the bow wave and wake will be infinitesimal on the model) and too low for the rudders to act as they would on the full size boat. One way around this would be to increase the stroke rate massively (which would look ridiculous and also be difficult mechanically) to achieve a hydrodynamically scale speed for the hull (Froude Number)

 

The other thing to watch out for is that wind effects scale massively for a small model. A very light wind is the equivalent to a full size gale and will stop the model dead.

 

I made a very simply model of a rowing machine, prior to starting on my Olympias model. Only 12 oars operating in a simple circular path:

I also produced a simple spreadheet to simulate the physics of the model and carried out some trials to validate the spreadheet with the model:

Rowing Machine Calculation.pdf

 

As you can see the model managed a speed of 91mm/sec at a stroke rate of 45spm. Quite slow and, but looked about right for the "scale".

 

I also tried the model out crossing a reservoir on Dartmoor. I chose a day with no wind at all and it looked quite convincing as it made its way accross the lake...I didnt have any rudders, so i could only go in a straight line!

Edited August 7 by Richard Braithwaite

[Ian_Grant]

Richard, you have a far better understanding of the underlying physics than I. Have you any ideas of what I could try? I can think of (1) a midships skeg (which Javelin does not think will work), (2) huge rudders, (3) internal water pumps which could act as thrusters by sucking water in on one side of the bow/stern and pushing it out of the other via nozzles hidden u/w, (4) modify software to shorten oar stroke on inside of turn.

 

I can find 6V water pumps for RC, self priming, but don't know what force they'd generate at 1 liter per minute.

 

I now regret my simple flat-bottomed hull design. Experiments are required but I just can't find the motivation right now. I've moved on to restoring my old 70's Marblehead yacht just to get something in the water this season.

 

At least yours went in a straight line! Mine always curves one way or the other.

 

Thanks for any suggestions you may have!

 

Ian

[Richard Braithwaite]

I think the best approach is probably to turn using the oars. I would prefer to stop oars on the inside of the turn (either out of the water or in the water for more effect). The boat should definitely turn then as it will only have thrust from one side.

Olympias (full size) achieved its tightest turns using a combination of rudders and rowing ahead on one side only, so using the oars to turn would be an authentic way to manoever .

If your boat is directionally unstable you could help that by fitting a skeg at the back end.

If there is any wind at all the situation will get confused as it will acto on the hull above the water to turn it one way or another - best to only use the model on a still day (or an indoor swimming pool!).

[Ian_Grant]

Thanks Richard. Yes, that's what I was doing before fitting the (ineffective) rudders. I backstroked on the inside which completely stopped the boat while it swivelled on its centre point but I can't do that every few seconds. I'm not sure it would even turn with oars stopped on the inside with my hull bilges; need to try some stuff before our pool closes.

 

Love your Olympias!

[Bedford]

As you know, I'm no expert in the field of quadrireme design or use so take this however you chose.

I own a 15 foot Tammie Norrie, a beautiful rowing/sailing dinghy with a bit much freeboard for rowing in windy conditions so I deploy the rudder in such instances.

 

My oars are 8 feet long so the motive force is at two points 16 feet apart in the water. That's a lot of leverage applied by each oar. To overcome that leverage with a rudder is not easy. I can tell you from experience that the boat can not follow the arc set by the rudder while being rowed. It goes straight and then when oars are lifted for the back sweep it takes the rudder a second or so to overcome the straight line momentum before imparting its influence on the direction of the boat. The boat traces an almost porpoising action but on the horizontal plane.

 

This is with a full scale rudder in full scale conditions. 

 

Another way to look at it is as a drag car. Imagine a locked differential driving two tyres 4 feet wide and trying to steer with 4 inch front wheels. It ain't going to happen.

 

The only way I can steer my boat in an arc is by altering the power I apply to the inboard oar and shortening the stroke.

 

So as I see it you either reprogram to achieve this or make MUCH BIGGER rudders. 

[Ian_Grant]

Thanks Bedford.....As always in this log your comments are insightful and got me thinking something might be done.

Now that the heat wave has broken I will try some experiments in the pool - skeg, LARGE rudders, software changes.

 

Ian

[Kevin-the-lubber]

Ian, left field, pragmatist thought - add a little hidden motor and prop at the stern, just to overcome the limitations of scale? Probably not what you want to do, but to a very great extent I think you've already achieved a lot and shown what's possible (and less possible) with oar power alone. 

[Ian_Grant]

5 hours ago, Kevin-the-lubber said:

Ian, left field, pragmatist thought - add a little hidden motor and prop at the stern, just to overcome the limitations of scale? Probably not what you want to do, but to a very great extent I think you've already achieved a lot and shown what's possible (and less possible) with oar power alone. 

That's what my engineering student daughter said the first time I had it in the pool. Sigh. 😐

 

There are a couple of videos of other galleys moving effortlessly through the water. I have often wondered if they have prop assist. One of them I think must have because the oar motion seemingly does not justify the speed.

 

It would be quite a major job to bash a prop shaft hole through the stern given the embedded lead ballast. 🙄

Edited August 8 by Ian_Grant

[Javelin]

The question is, does the veering off course happed due to wind or simply due to minute differences in the oars? If it is the latter, you might add a longitudinal skeg on the bottom, the length of the keel. This would make her more "course stable", however it will make her less manoevrable as well. I don't really expect a real issue when really turning on the oars though. The rudders will have even less effect if you do this. 

It could however reduce the veering off-course. 

On the other hand, if she just gets blown sideways, this will not help too much. 

If it's of any comfort at all, I'm also having issues with the wind on Chaconia, I really need a big calm pond to sail it as she doesn't have a bow thruster and the turning with the wind gives a very large turning radius.