Hi Paul, tugs are short an' fat, destroyers and subs are long and thin!
The ratio refers to the length overall divided by the maximum beam.
Basically the higher this ratio the faster the hull will move for the same power input! 😊 Snag, the higher the ratio the more it rolls - ask any old destroyer driver 😉 cheers 😎 Doug

Hey Doug, what does high length to beam mean?

thanks

Paul

PS apropos weights, my stripped out 24" Sea Scout is just over 1.2kg. 😎

I agree with 'power in reserve'. 👍
I didn't plan it that way but my Type 1A U-boat with 2x 380s outruns and embarrasses most wanna-be power boaters! 😉
High length to beam ration helps, as always.
For the same reason my HMS Hotspur H class destroyer is also no slouch.
😎

"pmdevlin, it's difficult to build heavy if you follow the instructions"

Yes it is, its also difficult when you didnt actually build the boat, it was originally built (as prev stated) circa 1962 by my uncle, with IC engine, and a straight running rudder, as he couldnt afford full rc gear back then. Im thinking Martin you have watched the video, and saw that the boats did plane, be it 30 knots or 300 knots, they planed, scale speed or not.

I also own a four footer which handles beautifully, and is capable of well over scale speed, but speed is only relative to the position of the throttle stick, we all build to our own required specifications, and our own take on the original, with some modellers license😊 I would rather have power in reserve, than not enough power.
The problem with my smaller 3 footer is at the time my lack of experience, resulting in a heavy boat, Now I own some fast scale boats, I dont need the performance from the 3 footer, so it can be rebuilt using a lighter motor, lighter power packs, and get rid of some of the unecessary weight to make it sit better in the water, and look better at slower speeds

work in progress, as it hardly gets used, its not high on my to do list😡

thanks for the weight Dave, I remember that your 3 footer performs very nice, and is light. Ill weigh mine this week, its buried deep in the man shed, thanks also rob, but its the smaller 3 foot weight I was after👍
Paul

Martin
I was just sharing a bit more info for the benefit of our members. I never said they were quick but did seek to support your view that they were not like the faster recovery vessels.
I agree some models are sailed at over scale speed but each to their own and if it attracts new modellers to the hobby all the better. We can always try to interest them in more sedate models once they tire of racing round the lake.
Dave

Dave, I'm not sure what your point is. I know all that stuff about Crash Tenders and I also know that 28 knots really isn't that quick! Lifting the front third (just) clear of the waves isn't saying much compared to a full on plane.
It's all academic as almost nobody gives a stuff about scale speeds. Belt your MTBs around like demented ducks, but it looks stupid on a Crash Tender, as it does on tugs and warships that are too fast as well. indeed, most people use speedboats too fast as well.

Martin

Paul my 34" Crash Tender is 1900 grams with LiPo. I do hope you are not going to remove all the fine detail on you model to reduce weight.
Dave

Martin
Crash Tenders were to be used for fire fighting and as rescue craft for Flying Boats after the war. The Comet put paid to intercontinental Flying Boats so the two boats were never used for their intended service and no more were ordered.
They were only intended for inshore use so range was never a consideration and the quoted speed was 28 knots.
During the War the RAF had many fast recovery vessels that were much closer to the MTB and MGB used by the Navy.
One of our deceased club members Brian McAllen actually worked (as a chippy) on the Crash Tenders during his service in the RAF marine branch. He made many models of Crash Tenders and all had massive Brushed motors and were very fast.
They look splendid on the water and possibly because of the Aerokits versions are very nostalgic for many of a certain age.
Dave

In response to Paul's question, the weight of my 46" crash tender is 6Kg without the main batteries and 7.2kg with.
It got wet for the first time today with brief dunk in the 'test tank', and it sits about 10mm above the waterline all round 👍👍.
I ran the motor up very cautiously while my son in-law held it tight, and the thrust even at about a quarter throttle is astonishing 😱.
I didn't dare run it up to full throttle or it would easily empty the bath 😁.
I just need somewhere to find somewhere to run it now, and the courage to 'give it some stick' to get it up on a plane (hopefully) 😉.

I did have the T-shirt, but wore it out on the staircase because I couldn't afford a speedboat as a kid!

Martin

Well if you have slide down the stairs with your knees under your chin and your backside hitting every step, then you've done it all and have the t shirt. But 30 MPH (26.0693)is till not slow.

Having once been the Editor of the Classic Motor Boat Association, yes, I have been at 30 knots. in my own Albatross. And faster than that in a Delta. it is like sliding down the stairs with your knees under your chin and your backside hitting every step. I've done that too.
You keep talking about MTBs. I'm talking purely about the Crash Tenders. 30 mph is not that quick! MTBs were quicker. They were longer and much more highly powered.

Probably why the Crash Tenders were only 2 in number and never saw real service, but they are so pretty!

Martin

So the Crash Tenders only had a speed of 30 knots and that isn't that quick. The scramble nets were used for recovering airmen downed in the water, they had to get to them quick. Have you been on the water at 30 knot's compared to in a car it feels a hell of a lot different.

British Power Boat 60 ft MTB. They were based on the British Power Boat rescue craft and were originally designed for the Royal Air Force but reduced to 60 ft (18 m) in length. They could carry two 18-inch (457 mm) torpedoes and achieve a maximum speed of 33 kn (38 mph; 61 km/h).

PT boats maybe, but Crash Tenders were not as fast. 30 knots isn't that quick and if they went everywhere on the plane they probably wouldn't have the fuel to get home!
2 Meteorite V8s are a very different matter to three Packards!

pmdevlin, it's difficult to build heavy if you follow the instructions.
Mine is built to Aerokits instructions , has a Taycol Supermarine and used a lantern battery (which Dad used to get for nothing) and it would do a nice scale speed on its marks.

Martin

Hi
Don't know of a film but ...
"Dog Boats at War: Royal Navy D Class MTBs and MGBs 1939-1945
By: Leonard C. Reynolds (author)
Paperback
ISBN13: 9780752450452"
Built of plywood and measuring 115 feet long, powered by four supercharged petrol engines and armed to the teeth with heavy weapons, the 'D' Class Motor Gun Boats (MGBs) and Motor Torpedo Boats (MTBs) were better known as Dog Boats and played havoc with enemy shipping in home and foreign waters. During three years of war they engaged the enemy on more than 350 occasions, sinking and damaging many ships. "Dog Boats at War" is the authoritative account of operations by the Royal Navy's 'D' Class MGBs and MTBs in the Second World War in Home, Mediterranean and Norwegian waters. As well as drawing on official records - both British and German - the author has contacted several hundred Dog Boat veterans whose eyewitness accounts add drama to the unfolding story.
£17 at Smiths 😉
cheers Doug 😎

Was't that the idea of the real ones they were built to plane as were the M.T.B's to get there quickly. To put out the fire's and rescue men from the water. I thought that's what the side net's were for. if you watch the film's PT109 and They Were Expendable and there is another one I have seen I think it was Called Dog Boats at War. in fast, send out torpedo's and get out fast. They look much better with them up on plane than just plodding through the water. Peter Du Cane designed them for that. I have a book called An Engineer of Sorts.

They where planning boats Martin, capable of 30 knots, look at this, the front quarter of the boat is out of the water



This model was originally built in 1962 and over time has gone through a coupe of refurbs, I made it way too heavy and it sits too low in the water. The brushless motor is too big, hence thinking of just swopping it with a smaller motor as it doesn't need to go as fast as I originally wanted a few years ago. its never handled very well, the spray rails are now worn and pretty ineffective. At slow speeds the weight displacement is all wrong, and its bow heavy, almost ploughing the water, and it takes too much speed to get on the plane, I think she needs a diet, new spray rails, and a rethink on the battery placement. Unfortunately its a boat that very rarely sees the light of day, it would be interesting to know what other peoples boats weigh, without batteries, if anyone knows?

thanks

If you're using Lipos, you could just reduce the number of cells to reduce the speed.

John.

The real ones barely planed, like most of their kind.

Martin

Where do you think the expression 'Give it some Stick!' comes from ? 😁😎

It does look a bit manic in those shots, but can't you just slow down on the stick?

Martin