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Author Topic: unknown fast boat  (Read 5104 times)

Ianlind

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unknown fast boat
« on: February 04, 2016, 05:16:52 AM »

I recently bought this old, well built timber and plywood model off Fleabay, along with a much larger F/Glass Hull, new and unused, just because the price was ridiculous.


Anyway this little speedboat hull was sitting idle taking up space, when my lady announced the other day she wanted a fast boat. I had only just built her Albert the tug, but she now wants something that will go quicker!


I don't have a clue what it is, but it's 635mm long x 250mm wide and came with a very worn propshaft and broken rudder and nothing else.
The propshaft is made from 1/8 bronze brazing rod, as is the rudder shaft, and the stuffing box bearings were, one missing and the outer one flogged out to over 4mm.
I turned up some new bearings and fitted a new S/Steel 1/8 shaft, as I didn't have any 4mm in stock. I then turned and tapped a bush for some plastic fast props I have in stock. I know that 1/8" is not a good size, but it will do for now until I can get some 4mm stock, next time I go to somewhere that might have it!
Trying to decide what to do about the rudder, as it is pointless putting 1/8" stainless in to replace the bronze, as I think it needs to go to 3/16 to minimise the risk of bending it, like has happened to the existing one. It'll be a pig trying to get the rudder tube out, as whoever built this thing did get some bits right!
So, the question is, does anybody have a clue what it is, and if so, do you have any idea about what the cover looks like, as I can't see any easy way of making something that will keep the water out!


Might have to go brushless on this one due to the shallow tube angle, otherwise a reduction drive will be needed.


Any help and suggestions appreciated, as I'm a Tug person, and this is my first attempt at getting something to go fast!


Ian.
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canabus

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Re: unknown fast boat
« Reply #1 on: February 04, 2016, 08:33:15 AM »

For that size boat I would go for a 28mm brushless motor( B28-57-15L 1900kv 750 watts( shaft 3.175mm), a car ESC 60A with reverse(these handle 2S to 4S batteries) Lipo battery 2650amh to 3000mah and 30mm two blade prop.
I used this set up on my 650mm Sea Hornet and I am get speed around the 40mph on a 3S battery.
On 3s = 21090 rpm.
On 4S = 28120 rpm.
If you put to large a battery in, the weight slows the boat!!!
I tested a 3blade 32mm prop, speed was about the same pick up was better but the motor got too HOT!!!
Run time with a 2650 mah battery would be a good 3/4 hour.
The 1/8 shaft would be OK but 4mm is the standard now days and dog drive props with thrust washer and lock nut.
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Ianlind

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Re: unknown fast boat
« Reply #2 on: February 04, 2016, 10:04:03 AM »

G'day canabus,


Thanks for the feedback. And I was expecting a reply from you!
I was thinking about a 28mm Brushless, as it will fit while clearing the inner keel. I wasn't thinking of going that high in kv, but I suppose I can try that for starters. Being a tug modeller I like to keep the revs down, so this is new territory for me!


My first attempt at Brushless was with Albert, and the 750kv motor is too small for running a 50mm x 4 blade prop, so the plan is, to take the small motor out and replace it with a much bigger unit, and try the small motor in the fast boat. It was using a 30 amp car esc, but it was getting hot and cutting out when it was run a bit hard. Runs OK at up to about 3/4 throttle with a bit of warming and no issues.
I'll be trying Albert this weekend with a 45amp fan cooled esc to see if it makes any difference, but I'll still be doing a motor swap next week.


Thanks again for your help,


Ian.
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canabus

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Re: unknown fast boat
« Reply #3 on: February 04, 2016, 12:15:41 PM »

The 750kv motors we use are the 35mm Hobbyking 3639-750kv 600watts on 2S(5550rpm)(about equal to a MFA 800 in rpm but 63 watts) or on 3S(8325rpm).
The 28 mm motors are not grunt!!!
One of the club members has a G60-500kv on 6S with a 70mm 4 blade but that's in a cabin cruiser and runs up to 31 mph.
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canabus

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Re: unknown fast boat
« Reply #4 on: February 04, 2016, 12:18:28 PM »

Another motor is the B28-57-17L 1700kv 630watts
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Ianlind

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Re: unknown fast boat
« Reply #5 on: February 05, 2016, 01:32:53 AM »

Thanks for the suggestions, but there is a problem with the 35mm motors, as there isn't the clearance above the inner keel. 28mm is fine, and I don't want to belt drive, so the larger motors are out for this job.
Also, I don't want this thing going too fast to begin with, as we don't have a lot of big water anywhere nearby, so keeping the speed down might keep it out of the trees!


Ian.
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canabus

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Re: unknown fast boat
« Reply #6 on: March 17, 2016, 12:26:39 PM »

Hi Ianlind
So the little lady requires a speedboat, but, out of the trees!!!!
The 3639-750kv 35mm motor would swing that prop for the Albert and 28mm motor(ex Albert) for the speedboat.
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Ianlind

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Re: unknown fast boat
« Reply #7 on: March 18, 2016, 02:45:21 AM »

G'day Canabus,


I ended up getting a bigger motor for Albert, but also got a 2836 1500kv for the quicker boat. Now just waiting for a set of props to turn up. They've been a long time coming, so I'm thinking they've gone missing in the system after many weeks of waiting. Problem is, that they'll replace them no worries, but then it's the long wait again!
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Ianlind

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Re: unknown fast boat
« Reply #8 on: June 11, 2016, 08:11:40 AM »

Canabus,


I've been a bit slack on this project for the last couple of months due to a lot of work coming in and needing attention, but I've now caught up and am back to some modelling for me.


I need your help on the rudder for this thing! I'm going with the 1/8th rudder shaft in 316 stainless for now, as I looked at drilling the original bushing out then reaming to 4mm, but it's probably not worth the effort, and the 316 stainless will be a lot stronger that the combronz rod previously used. I also had to increase the height of the rudder tube which was only about 32mm max height, and I reckon she might have taken in some water. It looks like the original tube was made from a 1/4 x 28 UNF brass bolt, so to increase the height I used a brass bush bored and tapped to suit the thread, then pressed that into a 3/8 thin walled Stainless tube 60mm long, which I then pressed another brass bush to the top end, and then screwed the tube onto the stubby one with some teflon tape to seal it. This new extension can now be packed with grease, where the original stubby tube/bolt could not be sealed at all.
I need an idea about how big I should make the rudder. I plan to use 2.4mm brass sheet silver soldered to the 1/8 s/steel which will be slotted into the blade for strength.


I've now fitted the 2836 1500kv motor direct/hard coupled to the propshaft, and it all lined up nicely.
Slow progress, but it's getting there!


Ian.
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canabus

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Re: unknown fast boat
« Reply #9 on: June 11, 2016, 08:52:30 AM »

Hi Ian
Slot the brass sheet to fit the rudder shaft, a lot easier to solder up.
I use two 3mm bits of 2.5mm silicone fuel tube top and bottom of the shaft.
Helps seal each end and the top one also if the rudder arm slips off.
Silicon plumbers grease works well.
Tube length above the water line if possible.
I found an old speed boat at the tip shop $15.
It had nose and bottom damage.
I have replaced the nose and cut 100mm width out of the bottom.
Removed the keel and add two stringers.
Ordered a new flex drive line, so it's on hold for a time.
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Ianlind

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Re: unknown fast boat
« Reply #10 on: June 11, 2016, 12:18:10 PM »

G'day Canabus,


Any clues as to how big I should make the rudder? I've done a number for tugs and other work boats, but new to this fast boat caper.


I use waterproof high speed bearing grease in my tubes which seems to work OK.


How about a pic or two of your find. I only paid about $30 for both the ply boat and the new and unused 3ft f/glass hull from the one seller on Ebay.
You can get lucky on occasion!


Ian.
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canabus

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Re: unknown fast boat
« Reply #11 on: June 11, 2016, 03:21:44 PM »

Hi
I had to resize pic.
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Ianlind

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Re: unknown fast boat
« Reply #12 on: June 12, 2016, 09:32:56 AM »

G'day Canabus,


Made a rudder today and fitted it, and now just need to pack the tubes and it's close to go. I'll probably give it a test run in the next couple of days prior to worrying about the paint. I've still got to work out how to make a top cover for it, but maybe just tape over some soft plastic sheet in the short term.


Lady still doesn't like the scream of these motors, so more than likely Albert will be going brushed. I've now fitted a smaller 35mm 3 blade prop, rather than the original 50mm x 4 blade and it runs cooler, but still screams at higher revs. Changed back to the 30amp HK controller which has smoothed the start and seems to have quietened it down a little, but the lady still can't handle the high pitched noise.
I told her that the fast boat must use brushless, as I don't want to go fast brushed. Anyway, we'll see how it all goes.


Ian.
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Ianlind

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Re: unknown fast boat
« Reply #13 on: June 13, 2016, 08:05:19 AM »

Well, I got a chance to wet it today out in the Mooki River, and am suitably impressed with no prior bath test.
Running 2836/1500kv with 32mm el cheapo 2 blade plastic prop, firstly on 2s x 1.3 but when I ran that flat, tried a 3s x 2200, and what a difference that made!
This boat really goes well, and except for a bit of a leak in a crack along the prop tube sealant, needs little doing except for a cover and coat of paint. Not bad given the price! It doesn't take much water over the top, as the overhanging deck really pushes the water down nicely and the top stays quite dry.


Lady loves it on 3S and when asked about the increased noise, after the  earlier complaints, she says it's different this time!! She just has to decide on a colour scheme before it gets a coat or two of paint.


The images are running of 2s, but I had the wrong camera with a shutter delay and had trouble keeping up with it! Didn't try and get any images on 3s as it was just too quick. Our new water, although a lot better than the previous billabong is still a bit small for very quick stuff with a lot of bullrushes around the edges, and not easily accessible for a lot of the perimeter.


Ian.
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Ianlind

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Re: unknown fast boat
« Reply #14 on: June 13, 2016, 08:33:21 AM »

My lady got an image on the phone camera running on 3s which shows the performance quite well.


Ian.
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canabus

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Re: unknown fast boat
« Reply #15 on: June 13, 2016, 08:49:19 AM »

Hi Ian
Add spray rails to the sides will help with the water problem.
Looks a good turn of speed.
Tell the wife red one's go faster!!!
Happy WIFE!!!
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Ianlind

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Re: unknown fast boat
« Reply #16 on: June 13, 2016, 11:45:32 AM »

G'day Canabus,


I don't think the spray rails are needed, as the extended deck width really pushes the water down well. There was very little water on the deck after around 30 mins of good running with plenty of full throttle turns, so I think I'll leave it the way it is for now.
Just need to seal the inside after it dries out and then sort the crack at the prop tube. It looks like it was installed with car bog and is very rigid and brittle so I'll seal it on the outside with Epoxy, as the one I use doesn't set rock hard.
While I'm waiting for the fast boat to dry out, I've got to re-power Albert with a brushed motor. Must admit, I'm not over keen on the whine of the Brushless motors either. Fine on aircraft as they are mostly further away than the boats are.


Ian.
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canabus

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Re: unknown fast boat
« Reply #17 on: June 13, 2016, 12:35:53 PM »

Hi Ian
 My Sea Hornet's is not noisy on 3S, but my other brushless motors are like Bengal tigers especially on 4S.
Also my outboard one sings on 3S(3000kv on 32mm 2blade prop).
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ooyah/2

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Re: unknown fast boat
« Reply #18 on: June 13, 2016, 08:51:36 PM »

I recently bought this old, well built timber and plywood model off Fleabay, along with a much larger F/Glass Hull, new and unused, just because the price was ridiculous.


Anyway this little speedboat hull was sitting idle taking up space, when my lady announced the other day she wanted a fast boat. I had only just built her Albert the tug, but she now wants something that will go quicker!


I don't have a clue what it is, but it's 635mm long x 250mm wide and came with a very worn propshaft and broken rudder and nothing else.
The propshaft is made from 1/8 bronze brazing rod, as is the rudder shaft, and the stuffing box bearings were, one missing and the outer one flogged out to over 4mm.
I turned up some new bearings and fitted a new S/Steel 1/8 shaft, as I didn't have any 4mm in stock. I then turned and tapped a bush for some plastic fast props I have in stock. I know that 1/8" is not a good size, but it will do for now until I can get some 4mm stock, next time I go to somewhere that might have it!
Trying to decide what to do about the rudder, as it is pointless putting 1/8" stainless in to replace the bronze, as I think it needs to go to 3/16 to minimise the risk of bending it, like has happened to the existing one. It'll be a pig trying to get the rudder tube out, as whoever built this thing did get some bits right!
So, the question is, does anybody have a clue what it is, and if so, do you have any idea about what the cover looks like, as I can't see any easy way of making something that will keep the water out!


Might have to go brushless on this one due to the shallow tube angle, otherwise a reduction drive will be needed.


Any help and suggestions appreciated, as I'm a Tug person, and this is my first attempt at getting something to go fast!


Ian.



Ian,
I think that your e-bay purchase is a boat called ASTRA and was featured in Marine Modelling   JUly 1993 and was designed for I.C. engines.

I bought the plans and had them enlarged to 2x the drawing giving an overall length of approx 50" into which I installed a flashsteam plant and eventualy had the boat timed at 45 m.p.h., spray rails are a must, here are 2- pics of the boat which I think shows the similarity.

Hope this helps.

George.
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tr7v8

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Re: unknown fast boat
« Reply #19 on: June 13, 2016, 09:58:15 PM »

Interesting, more infor on the flash steam plant please?
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Jim

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Re: unknown fast boat
« Reply #20 on: June 13, 2016, 11:32:28 PM »

Interesting, more infor on the flash steam plant please?

Try R&D in steam section I have already started a thread on it a few years back,

George

http://www.modelboatmayhem.co.uk/forum/index.php/topic,24568.0.html
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tr7v8

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Re: unknown fast boat
« Reply #21 on: June 14, 2016, 11:48:01 AM »

Thanks for that, that was 2 hours of no work following the links!
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Jim

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Re: unknown fast boat
« Reply #22 on: June 14, 2016, 02:26:16 PM »

Thanks for that, that was 2 hours of no work following the links!

Glad that you enjoyed the read, at least now you will now know a bit more on a subject that you never new about.

It only took me about  8 years to develope the steam plant and 20 days to write it up, so to enlighten somebody it was not in vain.

George
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canabus

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Re: unknown fast boat
« Reply #23 on: June 14, 2016, 02:56:09 PM »

Wife's are a good flash steam plant!!!
Especially went you come home with another project boat !!!!!

Canabus
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