Outside the box thinking – 1970’s Sea Commander

[Andy FParticipant @andyf73386]

About 40ish years ago I built a Sea Commander kit, which was good and I had many hours of fun with it but then I discovered things with wheels and things with boobs (both of which my dad told me were not good for me and would cause me grief. He was right, as usual). The boat lay unloved for many years and underwent several unsuccessful 'restorations' in many guises over those years, the latest of which is this one (below).I never really liked this version so I'm looking to do something different with it.

Has anyone got any ideas as to what can be built onto an almost standard Sea Commander hull without too much butchery? Ideally I'd like to keep the twin motor/twin rudder arrangement that one of the previous restorations left me with. I think it looks quite good.

[Andy FParticipant @andyf73386]

[Paul TParticipant @pault84577]

Hi Andy

The only way that I can see is to remove the superstructure, adapt the deck and put on a new superstructure.

Good luck

Paul

[harry smith 1Participant @harrysmith1]

Hi Paul T

What about a Swordsman or Sea Rover.

I have both plans as PDF which I can send to you.

Harry Smith

[Andy FParticipant @andyf73386]

I quite like the looks of the Swordsman.

What kind of motor/battery combo would I be looking at bearing in mind the boat as it is weighs in at a shade under 2.5 kg?

[ashley needhamParticipant @ashleyneedham69188]

Andy. What motors does it have in it at the moment, and are they inadequate or did it go ok . Basically, if it went ok, do the top first.

Ashley

[Andy FParticipant @andyf73386]

Whatever motors it had are lost to the mists of time but I seem to recall that they were nothing special, maybe 2 – 21/2 " long and run off a single 6v SLA battery and a single old school rheostat speed controller. It didn't go very fast but it was designed as a cruiser so that didn't matter too much.

Ideally I'd like a bit more woomph if possible but for some reason I'm scared of brushless.

[Ray Wood 3Participant @raywood3]

Hi Andy,

A pair of 600 size brushed motors and nicad s will give a good turn of speed 😀

Regards Ray

[Andy FParticipant @andyf73386]

A couple of questions arising from Ray's answer.

What's the difference between Graupner Speed 600 and Mtroniks 600 apart from 7 quid each? Do they operate equally well in either direction (the boat has opposite handed props, which I like)?

and

Why specifically Nicads?

I honestly have no clue whatsoever about electrical stuff, I'm here to be guided.

Thanks for the help so far

[Ray Wood 3Participant @raywood3]

Hi Andy,

I expect the Graupner ones are slightly better hence the price, yes the motors will run in both directions, I use buggy battery packs with old Tamiya plugs on much lighter than the old SLA batteries and can be fast charged at 7.2 volts one per motor should do the trick.

Regards Ray

[ashley needhamParticipant @ashleyneedham69188]

Ray of course means NiMh battery packs, not NiCads!

600 size motors would indeed do you, however not all 600ks are created equal, and there are considerable differences between them.

The Mtronics one appears to be fairly slow revving, and at 12v the spec says it will do 5200Rpm which is not much and at 7.2v might only do 3000 rpm.

The Graupner speed 600 rated at 7.2v produces 18000 rpm, at 7.2v.

The Aeronaut speed 600 is a 6-12v motor and it says develops 14000 rpm presumably at 12v. We could say that roughly on 7.2v you might have 8-9000 rpm on tap.

(all figures unloaded…which means just spinning whilst held in the hand)

So there we have it. Three outwardly similar motors with differing offerings.

As usual I would ask how fast do you want to go? In order, fastest Graupner, then Aeronaut and trailing, the Mtronics.

It’s horses for courses really. There is the brushless option but this gets much more complicated and will use two esc (electronic speed controllers). Unfortunately the choice here is massive and everyone has their own favourite setup. 

On the face of it, the Aeronaut ones are a halfway house, the Mtronics is for slower scale vessels hence the lower revs and high torque, the Graupner will deliver good performance using a smallish S35mm prop.

Ashley

 

Edited By ashley needham on 17/08/2020 08:39:39

[Ray Wood 3Participant @raywood3]

Thanks Ashley,

I knew you would know the technical stuff, I'm basically a chancer, but I remember when we used Graupner Speed 400's for flying years ago so they must be good

Regards Ray

[Charles OatesParticipant @charlesoates31738]

You also ask what can be built on to the basic Sea Commander bull. At the risk of saying the obvious, the original design is excellent, you could go back to that. Then you could make improvements, carefull use of veneers can make huge difference as can a well chosen carefully done paint job. Make it into a gentleman's cruiser.

Chas

[Chris EParticipant @chrise]

Posted by Ray Wood 2 on 17/08/2020 09:19:12:

Thanks Ashley,

I knew you would know the technical stuff, I'm basically a chancer, but I remember when we used Graupner Speed 400's for flying years ago so they must be good

Regards Ray

 

Sorry but I don't agree. I used to fly with 400's & to get any real power we abused them horribly and they didn't last very long. I used to carry a spare motor to the flying field.

Brushless are so much easier. They have a specification that easily lets you know what you are buying, they produce much more power for a given weight of battery & motor and are much more reliable when stressed because their limits are easier to comply with and there are no brushes to cause problems.

Thank goodness that the days of different 540's, 600's etc being sold as the same, but without detailed specifications, when they are in fact wildly different can be relegated to history.

For a displacement model I might still think brushed but for a planing hull it would be brushless every time.

Edited By Chris E 1 on 17/08/2020 10:53:53

[Ray Wood 3Participant @raywood3]

Hi Chris,

Yes I fly brushless & Lipos now, but back in 96 all I had was a S400 & 8 AA cells in a Model Designs FW 190 and it flew very well then moved onto the Blenheim which had 600's, those were the days

Regards Ray

[Chris EParticipant @chrise]

Ray

…..and flights that lasted 3 or 4 minutes. I am much happier where I am now.

Chris

PS Don't you just love the sound of a twin engined model aircraft

PPS Must stop this as wandering wildly off topic.

[harry smith 1Participant @harrysmith1]

Hi All

Totally agree with Chris E !!!

A good example is the banggood hobby surpass brushless motor, standard 540 motor mount.

Weight 132grams, 5mm shaft , a pick of three kv types.

Size 35mm diameter ,42mm long and handle 7-15volts(2-4S Lipo batteries).

The 1000kv 750Watts 55Amps.

The 1250kv 850Watts 65Amps

The 1450kv 1050Watts 76 Amps.

All Watt ratings are on 4S batteries.

I have a 30" Huntsman with a 1250kv on 3S and a good turn of speed.

Tested on 4S which turns it a bit of a speed boat!!!

 

As for brush motors the rock crawler ones are the only ones I found good specs on !!!

All on 7.2 volts(2S).

35 turn 13000 rpm, 45 turn 9500, 55 turn 7700 , 65 turn 7000 and 80 turn 5500.

The 80 turn I use in my fishing boats and handles up to a 3 blade 60mm prop.

Boat size about 860mm long( 2 Helens,1 Eileen and a French fishing boat).

Harry Smith

 

 

Edited By harry smith 1 on 17/08/2020 12:57:46

[ashley needhamParticipant @ashleyneedham69188]

Unfortunately advice regarding which brushless motors to fit on the forum tends to 100 pages with so many options that we get information overload, which is why I went with Rays suggestion.

Already Harry has put 8 motors up for consideration, they all work, or would work for him.

Dont get me wrong, All or most of the forthcoming suggestions will be ok in one way or another but deciding can be tricky.

Chris, would you therefor like to suggest a suitable combination?

Ashley

[Paul TParticipant @pault84577]

There is nothing like the sound of a big twin model aircraft doing a flyby, my engine of choice are old school Super Tiger 3000 as they are dependable and, with the right exhaust, sound super.

There is also nothing like the buttock clenching fear when you fly a big twin, if one of those motors die then you have massive Catherine Wheel on your hands closely followed by a big hole in the ground.

I'm always widely off topic.

Paul

[Ray Wood 3Participant @raywood3]

Hi Paul,

Yes I'm with you on that !! Electric twins are just not the same no risk of one of the fires going out

I use Savox servos, I find them very good.

Regards Ray

[Chris EParticipant @chrise]

Posted by harry smith 1 on 17/08/2020 12:57:18:

Hi All

Totally agree with Chris E !!!

………………………….As for brush motors the rock crawler ones are the only ones I found good specs on !!!

All on 7.2 volts(2S).

35 turn 13000 rpm, 45 turn 9500, 55 turn 7700 , 65 turn 7000 and 80 turn 5500.

The 80 turn I use in my fishing boats and handles up to a 3 blade 60mm prop.

Boat size about 860mm long( 2 Helens,1 Eileen and a French fishing boat).

Harry Smith

Or to make them comparable with brushless (dividing rpm by 7.2v):

35 turn = 1800kv

45 turn = 1300kv

55 turn = 1070kv

80 turn = 760kv

[Andy FParticipant @andyf73386]

So given the facts that:

a) I'm not flying a plane and

b) I don't want to go brushless,

I've decided to stick with the original suggestion of 2x Speed 600's. It's only 40 quid so what the hell.

Also, I'm taken with Charles' suggestion of going back to what it was (more or less) with a few cosmetic alterations.

Does anyone have a copy of plans for the Sea Commander superstructure they could let me have or borrow?

[ashley needhamParticipant @ashleyneedham69188]

Sensible decision Andy, they may not be the optimum, but they will be adequate. You can always do a straight swap upgrade later if the mood takes you.

Ashley

[harry smith 1Participant @harrysmith1]

HI Andy

I have a PDF copy of the Aerokits plan which I can send you.

Message your email address.

Harry Smith

[Andy FParticipant @andyf73386]

Thanks for the kind offer Harry but I'm way past that stage now, I decided to let my imagination loose and see what I came up with.

This is Pecola* as she stands at the moment. I tried the 600 motors but they (and the wiring) were getting way too hot for my liking so I replaced them with a pair of 385's and everything's good now.

As you can see, the boat has a fully detailed 3 cabin interior with working lights (so that all that work can actually be seen)…

…and the skeleton of a small jolly boat at the stern. That's what I'm currently working on.

I still have lots to do on her but so far I think she's looking good. Eventually the hull will be painted a nice rich gloss blue with a white waterline and red oxide below that. I also intend to put a large white swimming penguin logo on the bow.

The build/renovation has been a bit of a PIA because I originally built this boat nearly 40 years ago when I was young and stupid so consequently nothing is really where it should be. The motors for example have had to be mounted at an angle relative to the width of the boat because the prop shafts were mounted wrong in the first place and I didn't want to start messing about with them because they work fine. It looks OK now, just don't look too closely inside

* Pecola:

Pecola is a Japanese kids TV programme about a small animated penguin with a square head. I've named my boat Pecola as an homage to my works supervisor. He walks around like a demented penguin most of the time and he's a real PIA too so it kinda fits.

Thanks for looking.

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