Here is a list of all the postings Malcolm Frary has made in our forums. Click on a thread name to jump to the thread.
|Thread: Action P44 Twinlatch switcher|
Any switcher with heavy enough contacts can be arranged to do the job, but Tim's answer is the simple one that works.
Relays with contacts that can carry the full battery load tend to be thirsty when operated, and will tend to negate any benefit. Switching to a smaller capacity reserve battery to get you back "might" be viable, but really it is simpler to notice that performance has drooped a bit and bring it in. Having a switchable reserve is probably a temptation too far.
Edited By Malcolm Frary on 23/08/2020 17:04:44
|Thread: Ship Repair|
Some shops sell mast and spar replacement parts but they mis-label them as "chopsticks" or "kebab skewers".
I expect they think that the exotic eating market is bigger than that for model boat parts.
|Thread: Best Servos|
Over the years, there has been several changes inside my first Victoria (for comparison, about 400 sq in, weighs 5 lb, 30" long).
As bought second hand it was fitted with a standard servo, the manufacturer claiming it could be worked by one. As I found, it would only pull the sails in if there was so little wind that it wouldn't go. Probably why it found its way onto the CADMA bring n buy.
A "High Torque" servo from Howes worked great. Enough force, in light wind, to have the slack find the slide switch and switch the thing off. A radio boat that is now self steering on a large lake with shifting winds generates plenty of exercise. Thinking to figure out whwere its going, walking to get there, more thinking when the different wind close to the bank causes it to take avoiding action.
Over a few years, it did slowly bust its mounting box causing a rethink.
Small winches at a sensible price appeared (King Max)
A Victoria wants the travel that a 2-turn offers. 400 square inches is a bit too much for a 2-turn winch. A 4-turn required a bit of re-rigging, the winch line getting a doubler with a running block (or shirt button, as some call it) on the after deck to lose the excess travel and increase the available torque at the cost of speed. After a bit of a shuffle round of winches and models, it got a 6-turn. Same basic doubler, but the geometry of the deck bridle and boom fitting soaked up the extra.
Whether arm or single ended drum, a tension line is needed to keep the line being let out tidy. On a 30" boat, 5 or 6 of the elastic bands that come with bunches of spring onions do nicely, or you can go to a sewing shoppe and get an approprite weight of shirring elastic.
These small winches are superb mechanically, but to fit everything into a standard servo case, the electornics is maybe too tightly packed for its own good. This should not be a problem with larger winches.
Thats 11 years of sailing it like a hooligan.
|Thread: Ship Repair|
As Roger suggests, a slightly oversize hole up each part and an internal splint epoxied in place. Since it is decorative rather than working, a piece of toothpick rather than a metal peg would do.
If it wasn't so prominent, a bit of clear heatshrink might do the job, possibly forming a sleeve over Colin's superglue butt join. If the ends are jaggy enough, the butt join could well be enough by itself.
Edited By Malcolm Frary on 20/08/2020 22:44:34
Slec (one of the advertisers on this page) have a range of cabin cruisers. Depending, some should be large enough to fit out easily and use in a range of conditions while not being too intimidating as a project. Sadly, cabin cruisers lack sails.
Edited By Malcolm Frary on 18/08/2020 21:56:29
Slec (one of the adverisers on this page) have a range of cabin cruisers. Depending, some should be large enough to fit our easily and use in a range of conditions while not being too intimidating as a project. Sadly, cabin cruisers lack sails.
|Thread: Best Servos|
8 turns seems a lot. Much more usual is 3.5 turns. Most normal servos turn 1/3 of the travel of the pot on the inside, standard pots have a 270 degree track, so 90 degrees. To do a winch, the easy way was to use a "10 turn pot", 1/3 of that gave 3 and a bit turns, which was handy. With a normal transmitter, 3-and-a-bit might be it.
Measure from the chosen spot on the boom to the chosen rigging point on the deck with the boom full in, and again, full out. Subtract one from the other, if its a 1" drum, (3 and a bit inches per turn) you can work out how many turns. If it isnt too far out, jiggling the chosen points about can get the length the boom wants to fit what the winch will offer. Then try to do the same with the other sail.
At that price, it would have been rude not to get two. Maybe even churlish.
When picking a sail winch, apart from being able to fit it in the space available, you need to know the sail area and how much string is going to be pulled in. Some just throw the string on and fiddle with the electronics to get it right. It is much better to figure out the travel and tweak the layout of the string first.
Winches usually have a 1" diameter drum, so it is possible to work out the travel that a winch of however many turns will give. Arranging the running rigging (position on the boom, position on the deck) can make quite large differences, allowing you to trade speed and torque.
Arm winches do need a really strong mount to withstand the twisting that they generate - a drum just gives a straight pull. An arm is less likely to create a tangle, but is not immune from the problem. I have had one loop a loose line round the radio switch and switch it off. Amnnoying.
If the sails turn out somewhere in the 6-800 square inch range, anything that is good for an IOM will be fine.
Ever since it appeared a long time ago, the 1:72 Revell Snowberry corvette has been a good starter, especially for those with some previous modelling skill. Mostly just a bunch of new words to learn.
Fairly easy conversion to radio, big enough to get both hands in, small enough to carry to the pond, enough performance to look good, low enough performance to be forgiving.
|Thread: Best Servos|
Is this for the pond yacht? Knowing the size of the boat and its sail area helps a lot, along with the intended travel from full in to full out.
|Thread: A decent kit for a beginner|
Model Slipway kits build into superb models that sail well. Having said that, it helps enormously to have some boat model experience. Just an opinion, but something simpler and less complex might be a better start to give a working boat while easing the learning curve.
|Thread: 4 or 5 motors|
If it is for some reason vital that all of your eggs are placed in one expensive basket, fusing the individual motors is a must. You get exactly the same problems of equal or otherwise starting and responce caused by manufacturing variations between individual examples of motors whether using one big expensive ESC or three lower cost ones. Three correctly set up ESCs on one channel are no more liable to give uneven performance than three motors on one ESC.
If the 800 motors are 50mm diameter, 65mm props will be overdoing it and pushing the motors into their unhappy zone.
There have been cases where two sensorless brushless motors have been run off one ESC, but the guy who did it and videoed the result knew how to bend the rules. Anybody else is best advised to stick with the proven formula of one ESC per motor. Any problems are likely to involve less smoke release and be more easily solved.
What kind of battery supplies high current over a long time? A LiPo. More accurately, a really big LiPo. Probably as much as will physically fit, with a C rating that gives a comfortable safety margin.
Rescue methods vary with the nature of the pool. Size and depth, mainly, but the pond bottom needs to be considered.
The missile and line is very effective if you are confident of landing your missile beyond your boat rather than on or in, it.
|Thread: Pond Yacht|
In the 1950's radios generally fitted into a small sideboard, so originally, almost certainly a free sailer. A "serious" model would generally have some sort of steering correction, but there is no sign of a vane sitting on the stern, and no sign of the deck fittings that are associated with Braine gear. It might have a weighted rudder, but that is from a much earlier time.
i don't see any running rigging that might allow sail control by a radio if one got fitted later, but that doesn't mean that it is not a "steering only" model where the sails get set and you hope that as set they will give enough control.
The hull length might gve a clue as to any class it might belong to. On the other hand, it might have been built from a plan in something like the "Boys Own Paper" or similar to be a good looking boat intended to give pleasure sailing on a pond.
|Thread: Todays Boating|
Maybe something smaller like the auxiliary ark? The one that carried the unicorns and Bigfoot?
|Thread: 4 or 5 motors|
The ESC in the link is brushless, so not a lot of use for any 8xx series motors.
There comes a time when you might consider that one ESC per motor and a collection of Y leads might be a better solution than putting all the eggs in one basket.
|Thread: How to measure what motor I need.|
You can buy a rudder complete with a mounting tube, possibly with a tiller arm.
Also incredibly easy to make out of a wide variety of materials and generally using the simplest of tools. Brass sheet and rod works well, just needs a file,junior hacksaw and soldering iron. Balsa sheet and brass rod is almost as easy.
A quick google for "model boat rudder" should give lots of results only leaving you to search past the racing types that search engines are obsessed with. Scale types give a choice of brass or plastic.
|Thread: My new boat: Ramsey tug|
Just theorising, but no reason why it shouldn't work that I can think of.
There will be limitations, I am guessing from the number of terminals that it is as series wound motor. I only touched briefly on the things when doing my C&G studies a long time ago, but power dropped off considerably as current was reduced - it was a lose-lose situation. There was something about them behaving badly when fully powered if run unloaded, but thats back in the fog of time.
A motor, to drive, needs the rotating armature electro magnets to push against the fixed magnetic field. With a strong permanent magnet, this field is always the same. With a wound field, as the current drops, so does the power available in addition to what is lost to the moving coils because they have less to push against because the field coil has had its power cut.
So while it will work, it will almost certainly have different characteristics to a modern motor.
The servo operated reversing switch need be little more than a piece of copper clad stripboard under a wiper attatched to a servo arm arranged so that at one end of the servo travel, a common strip is connected to a length of copper strip going to the F terminal, at the other end of its travel, to the R terminal. At the mid point, nothing is connected, so you get an "off" position. Mechanically connecting a switch so that it both works and can't do either the servo or the switch or the mounting gets complicated.
|Thread: How to measure what motor I need.|
If what is needed is plenty of linear travel at a fairly sensible speed, there are standard servo size multi turn winches. 1,2,4,6 turns are available (called "sail winches". Also conrinuous rotation servos. Drum size is usually 1", so a bit of PiD gives the travel. Actual number ofturns depends on the transmtter, of course.
On a long, low hull as proposed, working hatches might be best if they just revealed a black painted panel rather than any hollow interior. A 2" ripple and gentle 10MPH breeze is seen by a 1:100 model as 17 foot waves and a 100MPH hurricand. Due allowance needs to be made. Any water getting on the deck has to leave it over the sides rather than down the inside.
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