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>> Home > Tags > vibration

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Sea Queen prop shaft by RNinMunich Fleet Admiral!   Posted: 2 months ago
Heartily agree Rex 👍 Two such couplings in series is a guarantee for misalignment and high vibration potential 🤔 which wouldn't do the 'posh' bearings much good! 😡 I would move the motor. Bon chance, Doug 😎

Sea Queen prop shaft by Rex3644 Lieutenant   Posted: 2 months ago
What is the KV of your motor and how many volts do you intend to use? The theory is that this is how it should be done and in practice I Have done this setup with Huco type couplings which turned over very smoothly but they could not handle the high revs ie14.000 The Radio Active couplings are first class but again I have experienced some balance issues and vibration with them. I worry slightly that the length of 2 couplings together is somewhat long but I may be totally wrong. All you can do is to try it I shall follow with interest

Too Powerful Brushless ? by BOATSHED Fleet Admiral!   Posted: 4 months ago
That sound better with a 5 mm shaft. But still be sure to support the shaft under the boat and if possible also under the shaft inside the boat. This way you shouldn't have any trouble with vibration though the shaft to loosen it.

Too Powerful Brushless ? by Dave M Fleet Admiral!   Posted: 5 months ago
Hi Graham Now we can see the actual prop shaft and motor it is clear that the shaft is not supported inside the hull close to the coupling. At the high revs your motor achieves I am not surprised you have had problems. I do agree with all the comments and help you have been offered and agree a 5mm shaft would help as well as a different motor. I use 3 blade brass props with brushless and have no problems but do keep the prop size to a diameter no greater than the motor diameter, as Mark advises. It's difficult to see how much space is in the hull to allow the motor coupling and shaft to be closer, but if you are replacing the shaft it may be a good time to reposition the motor and the shaft with the prop attached to a slightly different angle. This will mean opening the slot and perhaps enlarging the outside skeg but you can easily repair any damage with plastic padding to make good. Even if you keep the existing arrangement I suggest you provide support for the prop shaft close to the bearing as I suspect this is where you have experienced the problem with the vibration. A simple 2" block of wood attached to the keel and shaft would suffice. Model looks very good and I look forward to seeing some on water shots.

Too Powerful Brushless ? by jarvo Fleet Admiral!   Posted: 5 months ago
HI Graham. Every picture tells a story!!! The motor is definitely wrong, its designed for racing, low torque, mega revs, not for scale boats. What diameter is the shaft tube??? looks thin??? did the prop shear in the water?? would explain the vibration and damage to the shaft mountings, try a Raboesch shaft, with a ballrace at the motor end, great quality, also they do a huge range of props, google the name there site will come up. Mark

Too Powerful Brushless ? by onetenor Fleet Admiral!   Posted: 5 months ago
By the way the Araldite is very good glue but is brittle and as you have found cracks off with vibration. The other glues mentioned all have flexibility so will absorb any vibration.

Too Powerful Brushless ? by rmwall107 Lieutenant   Posted: 5 months ago
Hi traiderman I am no expert. dont forget, as pmdent highlights, you you multiply the KV by the volts of the supply to get the RPM of the prop. so you can play with the volts supplied or the Kv of the motor or both. regarding the vibration, have you supported the outer end of the shaft? if the shaft leaves the hull and has a good amount of unsupported shaft the end of the shaft effectively will scribe a circle. At the speed the shaft is turning and with the pressure on the prop this may cause your vibration. Richard

Too Powerful Brushless ? by pmdent Chief Petty Officer   Posted: 5 months ago
Traderman - whilst I am not an expert ( I am currently trying to decide what brushless combo to fit to a 34" RAF Crash tender) - clearly your motor is turing your prop shaft way to fast. With your motor spec of 3180 kV and a 14.7 V Lipo - your motor will be trying to turn your shaft at a speed of somewhere in the order of 45,000 RPM !! Firstly your prop shaft may not be rated for anything like this speed and secondly any slight mis alignment will likely be generating significant vibration - enough to cause your problem- have you noticed any? As to motor power - the motor may not be too powerful - but certainly dropping to a lower kV motor say 1100 and reducing the Lipo voltage to a 11 or even 7 volt system might be the right answer......but as I am finding its all a bit suck it and see... Peter

RE ads90's Vosper Firefloat by ads90 Commander   Posted: 5 months ago
Many thanks Dave and all. The reason I think it was a kit is because of the superstructure and deck detailing which you cannot see on my photos. All of the window frames have raised rivets around them and the deck has deck raised deck strips. As a modeller I know that these can be recreated but they look too perfectly spaced, etc. Many thanks for looking through your back catalogues Dave. Terry was very helpful and sent me quite a bit of information - he is a font of knowledge. My boat is well used at our pond at Eastrop, Basingstoke where I am the Secretary and Treasurer of the model boat club. Every couple of years I do have to give the hull a rub down and re-spray as being made from balsa and when running fast, the vibration does tend to crack the hull along the panel joint lines, but it is an easy fix and I try not to abuse it as it is precious to me.

Rudder Strut Assemblies by peterd Apprentice   Posted: 6 months ago
I am building from scratch a 35" Mini Momo and looking at the hardware required for the stern. Is there any great advantage to having a Z Type Rudder / Strut Assembly rather than simply having a Stinger and the separate rudder? To me they look like they could be a source of vibration or potential problems as they do not appear to be fixed to the stern at the location of the rudder. Thanks

Motor problem by RichardSReade Sub-Lieutenant   Posted: 8 months ago
Hi all I have located an 850 motor and mount at Howes Models in Kiddlington not too far from where I live in Malmesbury, for £22.50 however the prop shaft is 4BA, the coupling is not a problem as I can get the insert for the larger motor to fit the existing red coupling, but I can only seem to find 4mm 40 or 45mm propellers which are a fraction bigger than the 4BA which I know will screw on but they would have a bit of a wobble on the threads and could give me an out of balance vibration, apart from drilling out the old propshaft assy and fitting a new 4mm one what else can I do? or does anyone have a old 4BA prop they can let me have?

Aero kits Sea Queen by Rex3644 Lieutenant   Posted: 8 months ago
[Score: 8/10] 46" Aero kits Sea Queen Single Propellor (2 Blade X Type 45mm) Direct Drive to a 3650 watercooled (2 Blade X Type) Powered by Lead Acid (12v) 7Amp/h Batteries Controlled Through Hobby wing 100 amp w/c (100Amps) ESC - Comments: I felt the need to build something large from scratch having built Sea Nymph Sea Rover aero kits Swordsman kit. Many GRP based I/C powered before converting many of them to Brushless power. In Feb 2017 I bought plans from ebay in readiness for a family trip to Wales. My brother in law has a well kitted workshop in which he produced Sailing dingy kits before retiring. The aim was to produce this boat for the least possible cost. Thankfully there are lots of ply off cuts in Wales plus an 8x5 sheet of 1.5mm so I set about making my own kit during the time I was there. The motor was to be a Marx Decaperm selected from my bits box which I chose to set up using the geared drive. On the first launch performance was lacking to say the least so the motor mount was adjusted to direct drive but alas performance was not much better then everything stopped. The wires on the commutator had become unsolder end a common problem apparently I've now fitted a 3650 brushless stolen from an early attempt of a Huntsman 31 built for my Grand daughter which had replaced the Graupner 600, she is now 19 and interested in other things beginning with B. Having fitted the brushless a lot of vibration was experienced his was traced to a misaligned coupling,next outing will be with a huco type of fitting just to check it out roll on Thursday.

Seabreacher by Captain-Steve Chief Petty Officer   Posted: 9 months ago
Just spent a few hours fitting brushless motor to seabreacher....and 150amp esc ...problem working at these high motor speeds is vibration and motor has actually bent the driveshaft which is brass 6 mm step is new shaft of steel....

Crash Tender Shaft Tube Poistion by neilmc Commander   Posted: 10 months ago
Paul - luckily I have a new shaft as purchased one the other as Dave said about about making sure it true before fitting due to vibration issues later on if it wasn't true. Doug - I'm going to go for your's and Dave suggestion of fitting a fillet as to be honest it sounds easier and like Paul says its underwater so wont be seen and if it ever gets in the water wouldn't want to lose it on first trip out😁😁😁

Crash Tender Shaft Tube Poistion by pmdevlin Fleet Admiral!   Posted: 10 months ago
Neil, the suggestions about prop support are all valid, just different takes on things. I would (if you intend to repaint the hull) sand off to key, or prime the old paint prior to installing the shaft, as it will be easier to repaint and prep. Question, sorry if I missed this, is that a new shaft with new bearings? If not get new from shg marine (they are at the Blackpool, show, and the midlands engineering show if you can get to either, I'm not sure where you are?) they are dirt cheap, called aceteal or something similar, they water lubricate, and cost about £2 each. Roll the inner shaft on a piece of glass or a mirror, this will tell you if its bent, any sign of this, get a new one, or you might have alignment and vibration issues. (glass is totally flat! there's a free tip to test you prop shafts ha ha !!👍) same can be bought from shg, and get stainless. Back to the support, the thing Dave mentions is a piece of wood that fits between the hull, and the shaft. The shaft is then epoxied to this, giving support, but it wont be true to original. You have the original support, so remodel this to fit your new angle. If you use any bolts etc to secure, use stainless so they don't rust. Once painted, it will be hidden, and its underneath anyway so cant be seen. It will need to be tight to the outershaft, once positioned, you could solder, as they are both brass, and either feed into the hull bend over and epoxy, or screw as per original. Here is my big fireboat, its twin, but the concept is the same, the support came into the hull, and on this example, I put a brass pin through, and epoxied it all