Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Working Vessels => Topic started by: BeeJay UK on July 22, 2020, 11:28:43 am
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I am currently building a 'generic' Jersey 30ft fishing boat in 1/12 scale. I am using an old GRP hull that I have had hanging around for 20 years & I have bought a GRP 'cabin' from MMB. All the rest will be 'freelance' built, mainly out of ply, as I see fit.
Two questions though, power wise will the 540 I have be enough to run a 2" 3 blade prop to push a 32" x 13" beast around. Bearing in mind it is a bulldog not a greyhound, real life speed maybe 15 knots. Battery wise I have new 3S lipo's laying around or as it will need 6.5kg of ballast I may go for gel lead acid, which I would have to buy. I am open to suggestions.
Second question is regards to masthead lights on fishing boats, I have meandered around the internet and can't seem to find 2 sites that agreed. The standard nav lights is fine but what about the 'fishing' lights. I have seen so many variations so a definitive answer or a decent link would be great.
Thanks in advance everyone.
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It depends on the 540.
If it is a fast 540 it will overheat after making your boat into a speedboat.
Bob
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I have no idea whether it is a fast 540 or otherwise. I have no way of telling, I'm afraid that to me a 540 is a 540, I wasn't aware that there were different 540's. Things seem to have changed an awful lot in my 20 years away from model boats.
It is an MFA 457RE540/1 4.5 - 15v, if that is translatable by anyone.
I have got a brushless 1000kv motor or 2 laying around but brushless is even more of a black art for me.
Thanks.
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Lights vary with the length of the boat so check it out with Davie Tate on the site. nemesis
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Yes, under 30 metres or over 30 metres I think. As I'm only 32 feet then I'm definitely under 30m.
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I have no idea whether it is a fast 540 or otherwise. I have no way of telling, I'm afraid that to me a 540 is a 540, I wasn't aware that there were different 540's. Things seem to have changed an awful lot in my 20 years away from model boats.
It is an MFA 457RE540/1 4.5 - 15v, if that is translatable by anyone.
I have got a brushless 1000kv motor or 2 laying around but brushless is even more of a black art for me.
Thanks.
According to MFA's spec sheet the 540/1 is a three-pole, high speed motor. You should go with a 5-pole variant if you want to use 3S or 12v battery power with that size of propeller.
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It also depends on the boat: crabber, trawler, netter. So many small boats do different things. They all seem to have different rules and by admission on internet, some skippers just don't bother with whatever lights or daylight symbols because in reality nobody checks apart from an inspector on the day.
I'd agree though, no secrets with that motor and it's probably a bit too fast. Stick with general fag packet rule of thumb KISS where prop doesn't exceed motor diameter and number of blades doesn't exceed motor poles. Nothing much has changed much in last 30 years on brushed motors, I'd argue the choice is actually a little more restricted now than it was 20 years ago.
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According to MFA's spec sheet the 540/1 is a three-pole, high speed motor. You should go with a 5-pole variant if you want to use 3S or 12v battery power with that size of propeller.
Trouble is, I only seem to see them advertised as a 540 with no further detail so if I buy one I have no idea what I am actually getting & what it is suitable for.
I am toying with the idea of using a 540 with a 1 - 6 gearbox which the retailer claims to be suitable for scale. Even that is a bit vague too though.
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That's why it's best to buy from somewhere that lists the RPM at the nominal voltage (MFA does this) which allows you to match it to the maximum RPM of a particular size propeller (Raboesch used to have this info somewhere).
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That's why it's best to buy from somewhere that lists the RPM at the nominal voltage (MFA does this) which allows you to match it to the maximum RPM of a particular size propeller (Raboesch used to have this info somewhere).
A prop - motor chart would be great if such a thing exists. However in the absence of something like that us poor saps are blundering around in the dark. The general concensus of opinion seems to be that a 540/1 is not suitable with a 50mm prop. A 50mm prop looks right for scale I am building in I think.
However there is then the 'guide' from a certain retailer saying that a 540/1 is as follows. I read this as saying that it would be suitable. What do I believe.
"RE 540 3 - 9v 7.1A 10,800 Rpm @ 6v £ 6.95 A larger sized motor, also known as Speed 600 An industry standard general purpose high powered, high rev. motor for Electric Flight & Fun Fast Electric Boat Racing.
RE 540/1 4 - 15v 3A 13,360 Rpm @ 12v A larger sized motor same Dia casing as the 540 but wound for low drain and high torque, suitable for medium scale model operation replaces the old 545 motor which is no longer available"