Help & Advice needed please

Advert

New Replies

Report Bug

Help/FAQs

Help & Advice needed please

This topic is empty.

Viewing 17 posts - 1 through 17 (of 17 total)

Author

Posts
15 March 2013 at 21:51 #39688
Ken Buckfield
Participant
@kenbuckfield58436
Hi everyone. My name is Ken and I live in Suffolk. I already have 3 RC boats which I have been spending time on renovating them. I enjoy renovating old models that I either pick up at our local auction or form good old e-bay, but have to confess that I know very little about scales and related sizes, so please forgive my lack of knowledge here!

I have a Vosper Fire Tender which I am halfway through renovating at the moment. Having rebuilt many of the damaged/missing parts I am now in the process of painting this one. I also have a 36" cabin cruiser type boat ("Hawaii&quot and a much larger Cabin Cruiser too. The two cruisers are electric powered and the Fire Tender does not so far have anything installed other than a prop-shaft and propellor.

I have just recently acquiresd a massive model which is 54" long. It is a "Vivacity" Motor Cruiser designed by Vic Smeed. There is very little damage to this one, (nothing that a bit of glueing won't put right anyway). I would welcome any suggestions as to what type/size of motor or engine I should think about putting in. I don't mind either electric or fuel type, but have absolutely no idea what size I should be looking at. What I can say is that the boat weighs an absolute ton, and the person I bought it from told me that the previous owner had put a lot of weight in the bottom of the boat at the front to compensate for the weight of the engine that had been in it, although I unfortunately don't know what type of engine/motor this was. There is a prop-shaft fitted, and there appears to be mounts for servos the same size as in my other boats. I was wondering if something like a 12 volt motor like the type from an electric golf caddy might do but I would welcome any suggestions.

I think with a little work on the actual boat, it will look great on the water, but obviously I want to make sure that the motor that goes in it is going to be man enough for the size and weight of the boat. It does have a lot of led lights fitted to the boat, as well as a model revolving radar fitted to the wheelhouse, powered by a 12 volt motor set-up, so I do think that once complete it will be quite a nice looking thing.

Many thanks in advance to anyone who can offer any advice. I have enjoyed reading some of the various other posts on this site, which have been very interesting and informative.

Regards to all

Ken
Advert

15 March 2013 at 21:51 #2245
Ken Buckfield
Participant
@kenbuckfield58436
16 March 2013 at 08:39 #39691
Dave Milbourn
Participant
@davemilbourn48782
It might be worth considering a belt-reduction drive like this **LINK** The 850 version should turn something like a 75mm 3-blade prop quite handily on 12v, although I doubt from your description of the weight that it would get up on the plane. Removing some of that unneccessary weight would be a good place to start any renovation.
Any more ideas, chaps?
DM
16 March 2013 at 10:03 #39692
shipwright
Participant
@shipwright
Hello Ken,

Re Vivacity – the best advice would be if someone on this forum has constructed and sailed a Vivacity and could say what performance is achievable with motor 'A', ESC 'B', battery 'C'.

In the absence of that information I have a few points :

a. Have you measured the weight ? and have you put it into the water to see where the waterline lies ? (if it really is very heavy and lies low in the water it would be worthwhile trying to take weight out if that is feasible). I haven't seen an example of this model – is it a single shaft boat ?

b. What performance do you want – for example are you content with a sedate cruising speed or do you you want a more exciting performance ?

c. The answer to point b. above will be a determining factor as to what the power requirement will be. If you are not too bothered about performance then a 50 to 100 watt electric motor would be sufficient (as Dave suggested). If you want performance then you might require 200 to 300 watts.

d. Another factor worth noting is that there is a trade off between duration of sail time and speed – if you want to propel the boat at a reasonably fast speed then (for a given battery capacity) you will get a short duration on the water.

e. Although sealed lead acid (SLA) batteries look tempting in terms of number of ampere hours that you get for your £, they are very heavy. If you can afford the extra cost you would be well advised to fit NiMH batteries (Nickel Metal Hydride) – they are capable of delivering more amps than SLA.

Ian
16 March 2013 at 10:24 #39693
ashley needham
Participant
@ashleyneedham69188
Ken. A "fuel" type motor will severely restrict the waters that you can use it on, not a lot of places allow i/c motors.As there is one shaft, I would imagine..if the boat is of some age.. that is had a glow motor or something in it hence the single shaft. For a starter in any case, ditch all and any ballast weights in the boat as per Dave`s suggestion.

For good performance on a hull that size you are going to need substantial power on a single shaft, and you would need to look at the offshore racer boys set ups, although they will be using expensive gear.Probably a brushless motor would suit but I doubt if anyone on the forum could suggest a starting point on this one. There is a bewildering choice of brushless out there.

Gearing (via a belt) TWO 850 type motors to your shaft is an option, for cheaper power (even so the two motors will be £50) or of course fitting two propshafts would allow two 850`s, or 900`s from Graupner or whatever to be used . Two 850`s with X50 props would probably give a very reasonable performance, but still not of the planing variety.

Using Nimh batteries as suggested by Ian would give better performance in any case as

a) they give out the amps better and

b) they would be perhaps a third of the weight and thus increasing performance simply due to the boat being lighter.

Picture please. Create an album and load some photos on and then post them on a..post.

Ashley

LASTLY, as a suggestion….. just get a coupling, 850 motor, borrow a battery if poss, fit an X50 or three blade brass prop(not plastic, as they have very little pitch), remove the weights and stick it in the water and see how it goes! It may be that it is ok for what you want and so that will be that.
16 March 2013 at 21:33 #39709
Ken Buckfield
Participant
@kenbuckfield58436
Thanks very much Dave Ian and Ashley for all your suggestions, help and advice. I have listed below a few more details:

The "Vivacity" is a single prop boat with a 3 blade, single brass propellor. I drew a square around the propellor and the measurement from corner to corner of the square is 75mm. I have also weighed the actual boat on some bathroom scales and it weighs in at a massive 13 Kgs (just over 2 stones).

Regarding the extra weight, I don't think I will be able to do much about this, as there is nothing visibly removable inside the hull to create this extra weight, so I can only guess that extra weight in the form of cement or other such like material has been added during the construction of the boat. Unfortunately, I really can't see how any of this weight can be removed, without causing damage to the hull. I have had a look at the link that Dave kindly suggested for an 850 belt reduction type motor, but I'm still concerned as to whether or not this would be enough to drive the boat due to the weight of it. I haven't had the opportunity yet of actually putting the boat in the water to see how she sits, as Ian suggested, but I would add that I am not too concerned if I am only able to get the boat running sedately as opposed to it giving a high performance. I think for a boat of this weight and size, sedately would be much better anyway. As my 5 years old grandson is plaguing me to get the "big boat" running soon so that he can have a go with it, I think sedately is definitely the way to go!

Although I have several sealed lead acid, batteries I am quite happy to try Nimh batteries as suggested by Ian and Ashley, along with an 850 motor, if you still think this might work, given the very heavyweight of the boat.

I will try and take some pics of the boat tomorrow and add them as a post, as suggested by Ashley.

Once again, many many thanks guys for all your advice. Being myself very lacking in knowledge about these types of things, it is very much appreciated to receive help and advice from people who know what they are talking about, and it is very much appreciated.

Regards, Ken
16 March 2013 at 22:41 #39710
shipwright
Participant
@shipwright
Ken,

Have you now received sufficient information ? From your opening post on this thread I am assuming that you have installed the running gear into boats before and have the requisite knowledge about aligning motor and propshaft and using couplings, wiring up the motor, fitting interference suppression, ESC, receiver and servo. The 850 motor suggested by Dave will consume about 10 amps at best efficiency but note that in a stall condition the current can reach 60 amps (with 12 volt battery) – so ensure that the motor and ESC are protected with a fuse (eg 20 amp). I haven't used an 850 motor but I am fairly sure that both Ashley and Dave have had experience of that motor and could provide advice if required. Good luck.

Ian
17 March 2013 at 08:42 #39714
Tony Hadley
Participant
@tonyhadley
Hi,

Is it still necessary to fit interference suppression capacitors to the motor when using 2.4ghz radio control?

Tony.
17 March 2013 at 08:56 #39715
Dave Milbourn
Participant
@davemilbourn48782
Not strictly – but why would you not fit them as a matter of course? Your motor might just be "noisy" enough to affect other users' radios.
DM
17 March 2013 at 08:58 #39717
Paul T
Participant
@pault84577
Ken

So far everyone has assumed that you will have to fit electric power rather than a petrol engine even though this model was designed to have an IC unit.

The first and most obvious question should have been 'where will you be sailing'

Ashley is right in saying that the usual model sailing locations will probably be closed to petrol power but there is the possibility that you won't be sailing on a traditional boating pond.

As an avid builder of larger petrol powered models I usually sail on a local canal (where there are no Lilly livered restrictions on motive power) the models can achieve their full potential and can run for an hour without the need for constant changing of batteries.

Personally I would fit a 40cc two stroke chain saw engine into the Vivacity

Paul
17 March 2013 at 22:17 #39743
Ken Buckfield
Participant
@kenbuckfield58436
Ian,

Thanks very much for your reply. Although two of the my other three boats came already fitted with motors, esc's, servos etc. I learnt by taking everything out and reinstalling, as well as reading up in various model making mags, regarding what should be connected to what etc. The main thing I have limited knowledge on is scales and what size motors/engines should be used in various sizes of boats. It may be that the size/weight of this boat is too much for electric power anyway, so it might just be a case of trial and error if I can get hold of an 850 motor to trial.

If this is the case, I might just look at using a perol engine as suggested by Paul. There is a small lake at Snetterton Race Circuit, which is fairly local to where I live. It is owned by the huge Model shop there and open to anyone for a nominal daily fee, Also, there are no restrictions on using electric, nitro, petrol etc., so using a petrol engine wouldn't be a problem.

Thanks again for all your help and I will let you know how I get on.
17 March 2013 at 22:29 #39744
Ken Buckfield
Participant
@kenbuckfield58436
Paul,

Thanks very much for your post. The 40cc chainsaw petrol engine that you suggested certainly sounds a possibility, and I'm sure would be powerful enough to cope with a boat of this size and weight. As you have had experience of building larger type boats, I wonder if you could please tell me what type of speed controller and servos would be needed to use alongside this type of engine? There certainly seems to be enough room inside the hull to take an engine of this size. Also, what sort of problems have you encountered in the actual fitting of this type of engine? i.e. mountings, vibration etc.

I have actually got a large petrol strimmer, which doesn't work (as the spool assembly which actually cuts the grass is broken/missing), although the petrol engine itself is in good condition and runs fine. I'm not sure until I dig it out of my shed, as to what cc the engine is, but do you think this might be a possibility to use?

I would be grateful for any advice you are able to give me on this. Many thanks and I look forward to hearing from you.

Regards

Ken
17 March 2013 at 22:49 #39745
Ken Buckfield
Participant
@kenbuckfield58436
"Vivacity". My newly acquired model. 4' 6" long

Edited By Ken Buckfield on 17/03/2013 22:51:39
18 March 2013 at 07:30 #39747
Paul T
Participant
@pault84577
Ken

Your strimmer engine is probably around 22cc and is easily large enough to power Vivacity, I use a heavy duty servo to operate the throttle and a standard servo for the rudder, being a petrol engine it doesn't need a speed controller.

Vibration isn't usually a problem however you can fit rubber engine mounts which are available from some model shops (or ebay)

The biggest problem is cooling the engine, you can either convert the present air cooled unit to water cooled or fit some computer cooling fans to push outside air into the hull to cool the engine.(with a suitable duct to vent the waste heat)

I hope this helps but if you need any further assistance just ask.

Paul

I have to admit to being a little jealous as I don't have a Vivacity and have been looking to buy a second hand one for some time.

Edited By Paul T on 18/03/2013 07:35:17
18 March 2013 at 11:36 #39757
Ian Gardner
Participant
@iangardner62867
Just going back to Tony's question about supression using 2.4ghz, I have found it necessary. I have an MFA geared 500 in my Silver Mist model and even after the usual suppression methods I found the only way of quietening the motor was to wrap it in silver foil! The radio is the ubiquitous Planet. I have the same motor in another boat and that one wasn't a problem. Thought I'd mention it!

Ian
18 March 2013 at 22:43 #39768
Ken Buckfield
Participant
@kenbuckfield58436
Paul,

Many thanks for the info regarding fitting a strimmer engine into my "Vivacity" model, and for your advice and information. I think that I'll probably give this idea a go and see how I get on.I hope you don't mind me asking yet another possibly daft question, but you said in your post about using a heavy duty servo to control the throttl, and I wondered if you might be able to advise me on where would I be able to get hold of one of these, as I have no idea on this.

Fitting either cooling fans or converting the engine to water cooled as well as fitting rubber mounts shouldn't be too much of a problem, but it's the servo I'm not too sure about. Presumably, it would have to be linked to the receiver fitted in the boat to control the rudder servo etc, but having only ever fitted regular servos in my other models I have no idea how I could do this.

I actually got hold of this "Vivacity" as a "Buy It Now" on ebay recently. It had been on there for a couple of days before I finally decided to click on it and buy it, but I have to say that when I went to pick it up I was more than pleased with it, even though there is no radio gear fitted yet. It is in pretty good condition apart from one piece on the roof of the wheelhouse that needs re-glueing. It does have a large rudder which I need to fi,t as well as lots of other fittings for the deck including all the safety rails to go around the edges of the deck, so I think once it's all tidied up with all the parts fitted and is ready to put on the water it should look quite impressive.I have posted a picture of it and I will try and add some more pics later.

Many thanks again for all your advcie which is very much appreciated.

Regards

Ken
19 March 2013 at 08:03 #39771
Paul T
Participant
@pault84577
Ken

A heavy duty servo is fitted in the same way as a standard servo it just has higher torque. Connecting it to the carburetor on the engine is fairly straight forward and works in much the same way as a twist grip throttle on a motorbike i.e. it goes faster as it is turned.

Fitting a grooved pulley to the servo will allow the throttle cable to be operated (just like twisting the motorbike grip)

Sorry to bang on but its difficult to explain without diagrams so if you cant understand my blather I will sketch up a layout for you.

You might have to beef up the motor mounts in the hull to take the extra torque of the strimmer engine, if you are not sure just take a photo of the hull interior and I will be able to help you.

All the best

Paul
Author

Posts