Long term project 51" mono proposal

[Old School]

Mark, many thanks for your experience.

[rol243]

i would say the 8 mm shaft motors were more designed for car use as the off road car motors do take some hard hits on the drive train / gear.

[Peter A]

The 8mm shafts are less prone to flexing under high speeds and loads, especially on longer can motors. The clearance between rotor and stator inside is fairly small and the rotor contacting at high rpms will destroy a motor, hence the option of bigger shafts.

[Old School]

I understand that 3/16" flexshafts are more than enough for a 40 series motor but given that the hull is 51" then any 3/16" stinger drive is going to look rather anaemic. I wonder if the similarly sized Genesis 1.4 metre had 3/16" or 1/4" shafts. I know that 1/4" drives and stepped down 1/4" flexshafts were an upgrade item for the Genesis to take 3/16" props, however these have an unthreaded stubshaft and a single grubscrew retaining an expensive prop does not inspire confidence.

Perhaps I need to look at 56 series motors to get the beefier looking 1/4" drive stingers.

[rol243]

its worth a thought that when running an offshore type r/c boat that most of the time the prop or props leave the water surface as so the hull of the boat due to the choppy conditions that the model could be running in. so what happens when the prop /s leave the water whilst the motor / s is reving high then the props make contact with the water again and so on ?
there is alot of strain on the drive line and if the drive line is not of a good sound quality , something will eventually break.
look at your 51 inch cat hull for example; this is a big boat and when it is ready to run it is going to be heavy not like a small 30 inch hull which would be half or less weight plus offshore boating conditions are alot different to calm water lake running. so if i was the person building this cat hull for offshore conditions i would consider using 1/4 inch drive gear but for calm water lake running i would go for 3/16 drive gear of good quality.

[Old School]

I am thinking that the 40 series may be replaced by regular sized 56 series and thus 1/4" drives will be used. I need to await the hull and see how much room is available in the sponsons. On the 'factory' boat the stock 4082 motors do look small so space should not be an issue.

[srislash]

I think 40 series motors are a good choice for that hull. It is a dihedral design and handling would benefit from a lighter setup. Dihedral hulls are best ‘up on plane’ and running for maneuvering. Till then they are a bit of a tank.
A 3\16 flex is good for a prop up to 50mm with a good margin of strength. You should be able to find what you are after performance wise within those parameters. I think 1400kv on 6s would be a good choice.

I have 1/4” flexes on a 43” hull with Castle 1717’s(5mm shaft). There is a certain ‘security’ to having the larger shafts and perhaps less maintenance but it is a greater rotational mass with a courser wire within the tube. I bring this part up because I am looking at ways to gain some efficiency on said boat and smaller motors and smaller shafts may be the ticket. The larger motors do seem to like the amps. I did settle on 47mm props.

Just my thoughts, Shawn


PS: it runs good tho https://youtu.be/uuP1Bi1eISk

[Old School]

Wow, the boat is amazing.

40 series were my first choice as the factory set up has twin 4082 with 45mm props and performance at close to 70 mph on 6s is more than adequate for me. My concern is the choice of a stinger for each of the sponsons. I feel a 3/16" stinger would be rather small for a largish hull and that is why I was opting for the 1/4" stingers and consequentially 1/4" flexshafts.

[rol243]

https://forums.offshoreelectrics.com...m%2Fs14948.jpg

https://forums.offshoreelectrics.com...%2F24wsyyu.jpg

does over 125 mph on 10s.

[Old School]

At that speed my reaction time would be about 100 metres too slow.

[srislash]

Wow, the boat is amazing.

40 series were my first choice as the factory set up has twin 4082 with 45mm props and performance at close to 70 mph on 6s is more than adequate for me. My concern is the choice of a stinger for each of the sponsons. I feel a 3/16" stinger would be rather small for a largish hull and that is why I was opting for the 1/4" stingers and consequentially 1/4" flexshafts.

Well here is where I am thinking to go with stingers http://www.rcboatbitz.com/index.php?...roducts_id=811

You can get these in 3/16” to but I would maybe buy brass bushing(tube) to go to a 3/16 cable. Basically what Speedmaster does.

And look, local to you.

[Old School]

We think alike (I already have the 1/4" Speedmaster rotating bushes purchased for an ill fated project). These are what I was thinking of using. Yes, Joe at RC Boat Bitz is "local". My son has the 3/16" version on his Zonda.

Edit: on rethink, are you suggesting using 3/16" flexshafts in the 1/4" stinger suitably sleeved down to suit?

[srislash]

Perfect, you will have something to reference. You can just use K&S brass to sleeve it. But the bushings wouldhold grease better if you can incorporate one. I am all to familiar with a Zonda. Been picking away at a Fantasm for 4 years.

[Old School]

A word of caution. The Chinese based seller that I purchased my large cat hull from has responded to my query as to why firstly the supplied tracking number was invalid and secondly why it is overdue on delivery. I messaged him as the item was purchased four weeks ago and the delivery maximum time on EMS was expired three days ago.

He advised that while the item was prepared well it was found to be damaged on receipt at the shipping company and returned to the seller. All this happened in the last few days even though the purchase was made four weeks ago and a tracking number supplied at the time. I tried numerous times on the various online tracking companies but the supplied tracking number always returned that no information was available (probably because the item had not been posted??).

The seller has advised that a new hull will be shipped in the next few days and a tracking number supplied. If I had not have already purchased everything to outfit the hull then I would have started a dispute through eBay. As it is, with about $1000.00 in motors, ESC, drivelines, etc., to fit to the hull, I really cannot stop the sale proceeding as I need a hull. Definitely unimpressed that it took the seller four weeks to get the item posted and then did not tell me the item had been returned to him in the last few days as damaged.

[rol243]

This sounds a little suss to me as to why would the shipping company would send back an item that appears to be damaged unless it was squashed total, as opposed to just sending it onto the receiver . i have had damaged goods over the years and never had a parcell / box etc been returned to sender , it arrives at my home damaged. maybe this is true and theres nothing of concern but i would be making sure you have a working tracking number . if you used paypal as payment you should be able to recover any money if things go bad. fingers crossed .