New to boats, few questions.

[Forester]

Hi this is my first post in this area of rcgroups. I have been flying rc for over a year now and I have always wanted to build a boat. Anyway, I have a few questions about this.

1) Can I use my optic 6 transmitter and regular airplane receivers? I know that I will need a special forward/reverse esc to make it work though. I don't think that using standard servos will be a problem?

2) I haven't looked a whole lot, but it seems that all the electric motors are brushed type. Are brushless motors usable in boats?

3) I have scratch built a "flying boat" water plane with balsa and covered it with monokote. It does not leak even after sitting in water for 45 min. Is this the normal structure/covering for boats made from balsa? Marine epoxy?

4) Any other pieces of equipment that are boat specific, like a bilge pump? I imagine the thing will only be around 30-36" long, so it won't be terribly large.

This wouldn't be a scale job, but is there a place around where I could get some ideas on hull shape and design? I would like to build the complete boat out of balsa and plywood if possible.

Any input would be great.
Marcus

[LtDoc]

Marcus,
Your aircraft transmitter and receiver is not a good idea since a boat should be on a 'surface' band. There's always the potential of causing a crash by interference besides being illegal (them fly-guys get mad when you wreck one of their planes). Depending on how 'complex' the boat, most only need two channels, rudder and throttle, so an el'cheapo two channel ought'a work fine.

Brushed motors are most common with boats, at least the non-'Go-fast' ones. Brushless motors being sort of a higher rpm type of motor, sort of. They should work though.

The typical aircraft coverings (Monokote for example) would probably not stand up to the knocks that a typical boat will get, hitting the bank, other boats, who knows what else. Certainly possible, just not as tough as other ways of doing it. Laminating with balsa, fibreglass, plastic, and stuff that's tougher is sort of a good idea in most cases.

Specific equipment just depends on the specific boat. A bilge pump isn't a bad idea, but probably not really needed in most cases. More of a don't let any water get inside to start with thingy. At least not much anyway, sort of.

Hull plans... Probably more around than you might believe. Then again, probably not 'free' in every case. Got some idea of how you want it to look? How good are you at translating pictures into drawings? Just like the 'shape' of a cowling, the compound curves of some hulls ain't easy to 'do'. Since it's not 'scale', it could be anything you wanted, right? Sort of?

There are a great many model boats built with plywood formers and balsa 'skin'. Not really unusual at all, so certainly possible for almost anything you can think up. Another one of those 'sort of' thingys, some shapes are easier to twist wood into than others.

If you can build a flyable plane model there's very little reason you can't build a floatable boat. Weight isn't the 'biggy' with boats like planes, so it could be even easier. And also like planes, ain't nobody that's got just one boat, you know? And mistakes do happen...
- 'Doc

[Forester]

Thanks for quick reply!

Could i just collapse the transmitter antenna so the range would be very limited to use on the surface, at least until i could get another tx? I have lived in this area about a year now and have never seen even one person flying or rcboating. I have looked quite hard. That is still wrong I know, so I will see what I can come up with as far as a decent tx. What are the surface frequencys? 35, 36, 75, 2.4ghz?

I guess I like the brushless motors over the brushed ones due to the efficiency gain. either a high kv inrunner with a gearbox, or medium to low kv outrunner around 1200 or so depending on prop and power output? I guess i am wondering if there are any aditional water issues from brushless getting wet versus brushed getting wet.

So for a hull I could cover the built up balsa with several layers of marine epoxy? That would be about the easiest stuff for me to get around here since I am very close to lake michigan with boat supply stores around.

A boat that I would like to build is something like the attached picture. This isn't my boat, but the type that I would like to build, a ~25' powerboat cabin cruiser type, reduced to about 3 ft model size, maybe 1 or 2 motor inboard.

I am not really concerned with it being to scale. I remember seeing an awesome boat several years ago at the marina in Bayfield on lake Superior, and want to build one like it. I have never been able to find a picture to exactly match it though.

Yeah, i get you on the "can't have just one thing", I am working on building my 7th plane right now, I think that will be enough for awhile, unless I crash one beyond repair.

[LtDoc]

Marcus,
The 4 bands used in the USA are 27 Mhz (both air/surface), 72 Mhz (air), 75 Mhz (surface), and 2.4 Ghz (both air/surface). If you only want one radio system for both air and surface then my personal preference is the 2.4 Ghz, which has other good points, one of which is not being exactly cheap, so that's only a FWIW sort of thingy.

Are there issues about using brushless motors around water? Not that I'm aware of. At least I haven't heard any reasons why you shouldn't. Not having any direct experience with brushless motors, 'what I'm aware of' isn't exactly much to start with. I do know that brushless motors are more expensive (the ESCs too, if you want to be able to back up), and being naturally cheap, they aren't 'my' first pick.

Marine epoxy is certainly one way of doing it, and especially if that's more common than other things in your area. Would it be the 'best' way? Beats me, but I don't see why it wouldn't work.

Nice boat! Ought'a be a nice model too. Shouldn't be all ~that~ difficult to build. There's bound to be plans for such floating around somewhere. Don't ask me where, I have no idea.

Another one of those thingys about model boats is that they are never really ever completely 'finished'. There are almost always things you'll change later, or add, or that you decide you don't 'like' so it changes. Every boat model is different than the next one exactly like it (not sure that made any sense at all, but it's 99 and 44/100 percent true, sort of).
- 'Doc

[CG Bob]

There is a fifth band available in the US, if you have an amatuer Radio (Ham) license you can use the 50 or 53 MHz bands for any type of model. The only Ham rc system mad now (that I know of) is the Fuatab 9C series.

[johnmca72]

Thanks for quick reply!

Could i just collapse the transmitter antenna so the range would be very limited to use on the surface, at least until i could get another tx? I have lived in this area about a year now and have never seen even one person flying or rcboating. I have looked quite hard. That is still wrong I know, so I will see what I can come up with as far as a decent tx. What are the surface frequencys? 35, 36, 75, 2.4ghz?

I guess I like the brushless motors over the brushed ones due to the efficiency gain. either a high kv inrunner with a gearbox, or medium to low kv outrunner around 1200 or so depending on prop and power output? I guess i am wondering if there are any aditional water issues from brushless getting wet versus brushed getting wet.

So for a hull I could cover the built up balsa with several layers of marine epoxy? That would be about the easiest stuff for me to get around here since I am very close to lake michigan with boat supply stores around.

A boat that I would like to build is something like the attached picture. This isn't my boat, but the type that I would like to build, a ~25' powerboat cabin cruiser type, reduced to about 3 ft model size, maybe 1 or 2 motor inboard.

I am not really concerned with it being to scale. I remember seeing an awesome boat several years ago at the marina in Bayfield on lake Superior, and want to build one like it. I have never been able to find a picture to exactly match it though.

Yeah, i get you on the "can't have just one thing", I am working on building my 7th plane right now, I think that will be enough for awhile, unless I crash one beyond repair.

Plans for something like that ought to be found for around $15-20. Not quite free, but a drop in the bucket compared to the total investment you're likely to make when all is said & done. Check out Taubman Plans at http://www.taubmansonline.com/ for starters. For instance, under the "Pleasure Craft Plans", "Moon Mist" looks a lot like your photo ($15) or "Wolverine" ($17.50) is similar, but more sleek & modern.

If you're just planning to build something to cruise around with, & not try to win races, brushed surplus tool motors are easy to find & pretty cheap (I wouldn't pay more than $5). Plus, they'll work with a multitude of easy-to-find & inexpensive controllers.

Pick a large enough scale, & you can haul around plenty of low-tech, inexpensive batteries - enough to run long enough that you'll be bored or the sun goes down long before you run out of power.

JM

[LtDoc]

CG Bob,
OOps! You're right. But, in my town, 6 meters is so much of a bother that it isn't used for communicating, much less R/C'ing. One of the cable companies uses it as a 'translater' frequency and you wouldn't believe the nonsense they'll put you through if you 'interfere' with them. They 'DF'ed me once, years ago, and talked to half the neighborhood about all the interference I was causing. Luckily, my 'reputation' wasn't/isn't all that 'squeeky clean' to start with - lol. Their 'rep' decided not to press the issue when I asked him about 'closed systems' requirements, the current FCC engineer's name, and if he'd like his telephone number. While that shouldn't make a lot of difference, it can if you're 'blessed' with companies like that. Can you imagine the range you'd get with a 'gallon'n'half' output??
- 'Doc / W5LZ

[green-boat]

Their 'rep' decided not to press the issue when I asked him about 'closed systems' requirements, the current FCC engineer's name, and if he'd like his telephone number.
Good for you Doc, those big companies think that they can do whatever they want.

[Forester]

That is a good link to those plans. I think I like that Moon Mist one, and it would be close to the size I was looking for. To keep things lite and manageable, I was considering a smaller brushless setup with forward only esc. This would be much cheaper than a regular boat esc and motor setup at about $80, if I can keep it dry. Was looking at a 35mm diameter outrunner brushless motor with a kv of about 1400, running it at 30 amps on an 8 cell battery. This would be around 280 watts of power. Is that enough to get a boat like the one mentioned moving at a decent speed? I won't be racing with it, but still it needs to move along and not just put around. What kind of prop size/type would I need to get 30 amps with a 1400kv motor on 8 cells? Is there a boat motor calculator around somewhere?

I am sorry about all these basic questions. Thanks for the help so far.

[johnmca72]

That is a good link to those plans. I think I like that Moon Mist one, and it would be close to the size I was looking for. To keep things lite and manageable, I was considering a smaller brushless setup with forward only esc. This would be much cheaper than a regular boat esc and motor setup at about $80, if I can keep it dry. Was looking at a 35mm diameter outrunner brushless motor with a kv of about 1400, running it at 30 amps on an 8 cell battery. This would be around 280 watts of power. Is that enough to get a boat like the one mentioned moving at a decent speed? I won't be racing with it, but still it needs to move along and not just put around. What kind of prop size/type would I need to get 30 amps with a 1400kv motor on 8 cells? Is there a boat motor calculator around somewhere?

I am sorry about all these basic questions. Thanks for the help so far.

My favorite setup for 1:144 scale warships (up to around 6' long, but don't need to go very fast) is 2 Mabuchi RS-540SH surplus tool motors ($3.95 each, typically) powered by a MTroniks marine ESC ($50) with a 6V, 11AH gel cell batteries (about $18). I usually gear down about 3:1 or 4:1, but direct drive would probably power a decent sized cabin cruiser like that pretty well. Power draw is only an amp or 2 (about 10A stalled on weeds) & literally runs all day long.

A lot depends on the prop(s) as well. I drive 2, scale sized (I think 1-7/8" is the largest), with a pretty shallow pitch of 25º.

You definitely want reverse in a boat.

JM

[Forester]

I just found the Fast Electric Boat Calculator, but is there a way to input a different motors data besides what is on the list? Also, I have no idea on types of props, and there are a lot of choices there. Maybe I just need to spend half an hour going through each one on the calculator.

Are there any reasonably priced 40 amp brushless boat escs around? By that, I mean $70 or less.

johnmca72, where did you get those 6v batteries from and how large are they? weight? I might consider getting some of those and wiring in series to get a 12 volt source, if the weight isn't too much for a 21" long boat. My guess is that they are heavy though.

[johnmca72]

I just found the Fast Electric Boat Calculator, but is there a way to input a different motors data besides what is on the list? Also, I have no idea on types of props, and there are a lot of choices there. Maybe I just need to spend half an hour going through each one on the calculator.

Are there any reasonably priced 40 amp brushless boat escs around? By that, I mean $70 or less.

johnmca72, where did you get those 6v batteries from and how large are they? weight? I might consider getting some of those and wiring in series to get a 12 volt source, if the weight isn't too much for a 21" long boat. My guess is that they are heavy though.

I've bought mine locally, but the brand is CSB: http://www.csb-battery.com/

The model I use is obsolete, but the closest currently offered is GP6120 (6V, 12AH - 1 more AH, same voltage, same form-factor, & I'm sure the same weight, within any reasonable ability to measure (4.08 lbs). I put 2 of them in a battleship; smaller models are available.

Keep in mind, you're not limited to building the exact scale of the plans. If you build larger, the displacement increases geometrically vs. length & width, so a doubling in length will give you lots & lots of room inside, plus the ability to carry more weight (which means batteries, which mean longer run times). Larger craft also handle winds & waves better than smaller ones & you can see them a lot farther away.

JM