Something a bit different! Model Power Boating. RC Catamaran build thread.

[Phate]

Hello!

So a couple of weeks ago I purchased this!

It is a 48" long "Orion" Catamaran boat produced by Dave Marles of Prestwich Models. When I posted it in the purchased thread, some showed some interest in a build thread. Well today, yesterday, and for the next 9 days I will be going into this at full steam. Maybe even squeeze in a test run next weekend! Lets see

On the flip side, if this thread dies on its butt, then mods can delete it

So without further a do! Let's get into it.

First up, I need to find the centre of the boat to fit the drive strut and then rudder, also make up a plywood based brace for them to screw to. Most boats come with one of these already, however this didn't, nevermind eh.

Made this up, fuel proofed and then fitted inside the hull against the transom.

With that in, I found the centre then proceeded to get the drive strut & rudder bolted on.

Next up, water inlets, outlets and handles.

From here, its ventilation. I have 3 air scoops to fit to the front for intake then 4 exhaust ports for the rear for air to vacuum out

Exhaust vents first.

Positions figured out, time to dremel.

Nasty stuff this carbin fibre.

And that about does it for now. I've got more to add, but I would like to get some better photos of the finished vents first

Anyway, that will do for a first post...

 

[Yadda]

Great stuff. I've been looking forward to this.

 

[ArchAnGeL]

Will you be doing fpv with it? That would be cool. I love it when I see it done on RC cars.

 

[vanpeebles]

I used to know someone who was well into building and racing these, he went all over with them.

 

[PermaChanged]

Are you going to run this brushless electric, or petrol / nitro?

 

[ianh]

True story (sounds made up I know but 100% true) - I had a little 2ft radio controlled battery powered "power boat" as a kid and, in my last year at high school, for my CDT assignment/practical I decided to build a balsa-wood catamaran power boat (a small version of @Phate's) so I got a decent set of modelling diagrams and started building following a "Part 1" set of instructions from a library magazine. After the build was complete I transferred all the RC gear into the new boat, got a great grade on my assignment and took it to a local pond for testing.

It was 1 minute into testing on the pond that I realised I probably should have read the "Part 2" magazine which I'm guessing was "How to water-proof your new balsa-wood boat so it doesn't fall apart", as my water logged boat slowly sank in the middle of the pond as the balsa started to fall apart, with some the electrical gear shorting out and generally ruining most of it. After wading into the pond to recover the remains I took it back home where the unbelievably stupid excuse I gave my dad later after he saw the aftermath was, and I quote for the stupidity, "well wood floats doesn't it!!!"

 

[Nitefly]

Looks cool, good luck with it!!

 

[rodders]

We had a catamaran mould once, never ever finished it though!
See you mention fuel proofing, why are you going nitro rather than electric?

 

[morbid42]

The delivery guy looks very suspect

 

[Phate]

Lots to add after another busy day in the shed but I've had some wine so I'll update tomorrow

In short

- the engine is in and hole cut for the propshaft
- started to build the braces for the fuel tanks
- figuring out layout for the radio box

To answer some questions...

Will you be doing fpv with it? That would be cool. I love it when I see it done on RC cars.

No. I think it would be too disorientating. I have some GoPro footage from my Sprint Cat which I don't think will be as fast as this and that looks mental as it is - I'll get that on YouTube soon

Are you going to run this brushless electric, or petrol / nitro?

Nitro. 15cc. I've got a CMB 91RS M-Line to put in it.

We had a catamaran mould once, never ever finished it though!
See you mention fuel proofing, why are you going nitro rather than electric?

I just find it more interesting from an engineering and technical perspective. Electric is faster yes, but my goal is not to be the fastest thing on the lake. Nitro is more fun as it's more involved IMO.

Tbh I don't like gas/petrol engines. They're too loud for my tastes.

Glad there is some interest here. I'll keep the thread going

 

[LuckyBenski]

A) following because this is bonkers. Pretty sure I saw you say "50mph" in the other thread!

B) PLEASE start wearing gloves or at least a mask to work with CF especially if filing and sanding it. It really is nasty stuff and it'll get into your skin and lungs.

 

[Phate]

A) following because this is bonkers. Pretty sure I saw you say "50mph" in the other thread!

B) PLEASE start wearing gloves or at least a mask to work with CF especially if filing and sanding it. It really is nasty stuff and it'll get into your skin and lungs.

I am wearing a mask at all times when there is CF particles around. Rest assured. Haven't been wearing gloves unless dealing with certain solvents though. It's recommended for CF Dust as well?

And yeah I am expecting something like 50mph from this

 

[Deleted member 651465]

Sorry to bring my work hat to the table but please please please wear proper PPE if you’re grinding or cutting carbon fibre.

Exposure through inhalation is harmful and not to be taken lightly. A simple paper FFP3 dust mask can reduce exposure levels by 10x (assuming you’re clean shaven and wear it properly) and they can be bought in packs of 100 for a few £.

Looks like an epic project, I read the OP and already realise I know nothing about boats! Lots of words that were alien to me

 

[Phate]

Sorry to bring my work hat to the table but please please please wear proper PPE if you’re grinding or cutting carbon fibre.

Exposure through inhalation is harmful and not to be taken lightly. A simple paper FFP3 dust mask can reduce exposure levels by 10x (assuming you’re clean shaven and wear it properly) and they can be bought in packs of 100 for a few £.

Looks like an epic project, I read the OP and already realise I know nothing about boats! Lots of words that were alien to me

No absolutely! Safety first. Maybe I came across a bit blasé in previous posts however ultimately it is messing around with power tools, chemicals and lord knows what else and we've been doing this since I was a kid with guidance from Dad and we're still here with all fingers intact for a reason

I did actually check with a friend RE the carbon fibre and dust particles before I began cutting into it the other day and he gave the same advice regarding a mask straight away.

The mask I'm using is paper based with an actual filter on it. I'll post a pic later.

 

[LuckyBenski]

I think the jury is out on dust versus carbon fibres themselves. Probably less of a risk but it can't hurt to be safe. Ironically I did come across some advice on rcforums which I bet you've already been to a few times!

 

[Phate]

Indeed nobody ever died of wearing a dust mask when they shouldn't have

 

[Phate]

OK build log update 2, I'll try to pickup from where we left off last time.

So the holes were cut for the vents, then I made a wooden fixture out of ply to go under each vent hole and to allow the vents to sit at a pretty flush fitting with the body of the boat. After these were stuck in, the vents were then screwed into them, the resulting finish I am very happy with.

Rear ventilation done, it is time to work on the front. I have 3 air scoops to fit to the front of the boat for intake, mostly fitted around the front middle of the hull, giving some downward pressure to stop the boat flipping and keeping it a bit more stable. Also with them being in the middle and the rear vents being spread across the back this should (I believe, in theory) create a vacuum and help pull the air through the boat.

Approximate position decided after trailing a few options, this was my preference.

First one fitted

Remaining fitted

Next up is autobailers. Typically I fit/have fitted just 1 per corner/spontoon but I am going balls to the walls with this so I have double up, fitting four in total. No boat ever complained of removed water too quickly from it right?

Initially my main goal was to get the external stuff done first as it generally generates the most mess and I am trying to protect the engine from flying particles unnecessarily entering the engine. That being said, pretty much all the externals is now done and its time to focus on the internals, which brings me to the engine.

Some have asked what will be going in it. I've chosen a CMB 91rs M-Line which is a 15cc nitro engine. I went with this for a few reasons...

- My brother has a gas engined, and frankly the amount of maintenance he has to perform on it every single week is off-putting. I am not in the UK often enough to maintain it properly, plus they're so loud you can't really hear yourself think when they're running. It is annoying to me.
- Electric whilst will be the fastest...is a bit too disconnected in this instance
- I have always wanted a CMB engine, they're the best in the business. Hands down.
- The CMB 91 M-Line is rated for 7.0bhp, the Tiger King 27cc petrol engines (like my brother has) are at 7.6bhp. There is also a significant weight difference between them, with mine being much lighter which I believe will make up the difference. Although frankly speaking, I am not trying to be the fastest on the lake anyway.

Speaking of the engine, here it is.

(ignore the fact the engine mounts are upside here, I did not realise at the time of taking and this has been since corrected )

Now, unfortunately I did not take any photos of the engine mounts being fitted to the rails inside the boat, they're pretty clear in a few photos time but after much measuring and double checking they went in and the engine is now "in"

From here the next step is the prop-shaft. This also involves cutting a strip out of the hull along the bottom to allow the prop-shaft to pass through to the prop-strut. One chance at getting this right *gulp*

Measurements taken, boat masked up for guidance and then moved outside due to pending carbon fibre dust...

One of these...

Safety first!

Now we have a hole!

Test fit with prop-shaft without brass holder

Angle looks good.

Overall view of the boat.

To fix the prop-shaft in place I really need guidance from Dad here, it is the only part of the boat I am just not sure or confidence in doing, this will be done tomorrow morning. In the meantime, I did a bit more and got the fuel tanks in place.

First I removed the engine (much easier to fit/remove tanks with the engine not in the way as they will sit directly behind/infront of the engine just under the air vents) - then I made a backplate out of ply and 2 additional front wooden guides to keep them in place. On the backplate I cut some velcro to fit then glued this into place and the front guides - this has resulted in snug fitting not moving but yet at the same time removable tanks (if needed)

I also fitted the mounts for the radio electronics box arm to hold it in place, quick test fit shows its holding well (I picked up the entire boat with just the radio box and it didn't move, good enough) (also totally forgot to photograph the wooden backplate before putting the tanks in, doh!)

While waiting for Dad to be able to fit the prop-shaft I can work on the layout of the radio box. I have been working on this on and off over the last 2 days. But first, a couple of things to note. First is the servo for the rudder, this is pretty special and certainly far from a "standard" one

It is a Hitec D956WP IP67 Waterproof digital servo. This has a crank torque of around 25kg - typical servos range from 1kg-5kg although for moderately sized boats an 11kg servo is pretty common. For those wondering, this is so when the boat is travelling at full speed you can snap the control stick left or right and it just will not hesitate in turning the rudder and moving a boat of this size regardless of the force of the water hitting it. If you ever build one, one thing you do not cheap out on is the rudder servo. It could be the difference between saving or losing your boat!

Next is the battery

I went with a LiFE battery over a standard one due to going for digital servos. Analog servos with traditional batteries "pulse" 50 times a second, however digital ones pulse 300 times a second, this is comparable to framerates on your monitor, more pulses equals smoother and more precise operation. To achieve this, you need a battery which can deliver this power requirement. The downside to these batteries if they are a bit err...delicate. So I made a holster for it inside the radio box.

Lined with bubble wrap so it does not feel any sharp impact and a tight fit of the fixed wood either side ensures it has a snug fit. You can actually pick up the radio box via the battery once its pushed in, meaning its unlikely to come lose during travel.

Also, to charge these you have to remove them from the boat as they can be very unstable and explode without warning - using a holster in this fashion allows it to be seated properly and removed with ease as required.

------

That is it for this build log. I didn't really work on the boat today as we were out for the day, however I'll be piling more hours into this both tomorrow morning and evening (while taking other boats to the lake during the day! ) so I'll have more updates soon, the next one should be with the prop-shaft in place

Hope you're enjoying and thanks for reading!

 

[Phate]

Side note, I've got time this evening. I'll see about getting some GoPro footage up from my other boat.

 

[Drollic]

How do people tend to rescue these in the water if the engine cuts, spark plug burns out etc? A friend used to run a pretty expensive electric one and whilst a lot of fun, I always wondered how he'd fetch it if there was a problem. Guess you could swim

 

[Phate]

How do people tend to rescue these in the water if the engine cuts, spark plug burns out etc? A friend used to run a pretty expensive electric one and whilst a lot of fun, I always wondered how he'd fetch it if there was a problem. Guess you could swim

Swimming isn't really an option, especially at this time of year. The waters are too cold and without the proper gear you could end up in trouble very fast!

Each decent club *usually* has a rescue boat, which often is a plastic bathtub of a hull and battery powered outboard engine, so if it cuts out....you jump in and go and get it

Before rescue boats or places without them people either bring fishing rods or you can now buy electric rescue boats which have big open arms on the front (think of SpaceX and Mr Steven) to go and push it back to you.