Aerokits 46" twin screw brushless conversion

Started by pmdevlin

72 updates 6 likes 185 comments

Aerokits 46" twin screw brushless conversion

I have had a few enquiries regarding different parts of my boat, so thought it might be interesting to feature the blog here, seeing as this is the spiritual home of Fireboats!
I'm certainly no expert, most of the idea's were "borrowed", and I had considerable help from HS93 Peter Henshaw, who sadly did not see the end result.
I would like this to become a conversation, whilst the boat is now finished, it will be interestring to see if anybody has any other ideas to share. The build was originally on another forum, so if you read it there, this will be pretty much the same, sorry! if you have not seen it before, there maybe some parts of this blog that will help you save time, or money!, so thanks to Peter H for his inspiration, and Peter D for starting me off all those years ago!
Here we go........
1 comment
  1. Pete D
    Master Seaman
    HI P D, very nice of you to give me a breif mention in your blog, looks like a terrific job mate, HS93 would have been proud of you, the motor that was in it was either a Hectoperm (large motor) or Decaperm (smaller motor) you got the right price for it, I look forward to seeing the model in the flesh so to speak then I can critcise it forever (only joking Paul), look forward to seeing more of the blog.
    Regards as always,
    The other P D.

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Aerokits 46" twin screw brushless conversion

The boat was rescued summer 2010 from ebay, soundly made, true and square, never run or put in the water, circa late sixties, and sat in a loft ever since. it lived in the south Wales area, difficult to get to, and no postage offered, so for £75 I think it was a steal for this very original old girl

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Aerokits 46" Fireboat twin screw brushless conversion

On bringing it home, I stripped out all the junk, and sold the motor on ebay, it had never been run, I didnt know what the motor was, but it fetched £60, so the boat now owed me £15 , it gets better and better though, where do you store a big four foot boat???, well I also dabble with RC helis, and found on a helI website a "damaged parts" sale, I was real lucky to find an ally box, just the right size, reduced from £125 to £15, wanted a couple of repairs to it, but what a steal!!
So I now need a boat that looks the part, as I am turning up with what looks like a custom made box!, real show off! 😯

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Aerokits 46" Fireboat twin screw brushless conversion

After 12 months in the loft, summer 2011 its time to make a start, so off with the paint!, what a terrible job, don't know what it was painted with but it WOULD NOT come off, then when things seems to be at their darkest, my mentor (a very patient fellow HS93) suggested fairy power spray, yes you read it correctly, Fairy power spray,

At this point I would have tried anything, used sanders, scrapers, thinners, nitromors, next was a flame thrower, so sprayed it on, left it for a bit, and gentle scraping, it all fell off , no caustic smell, of chemicals that render the boat unpaintable, flippin great!

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Aerokits 46" Fireboat twin screw brushless conversion

Next bit is horrible, preparing for the paint. With my smaller 36" Fireboat, it suffered after time with delamination, so I decided to fibreglass this boat, I had only done this once before, so was dreading this job.

The photo is the fibreglass used for the hull, and a better brand for the deck, which is thinner and easier to apply, I wont need as good a finish on the deck as that will be painted with a none slip finish, as per real boat. The superstructure cabin sides will not need to be fibreglassed, more on that later, a bit of a trick coming up there 😉
8 comments
  1. Flack
    Warrant Officer
    Thanks for all the replies - head is now spinning, just spent an hour with a local specialist epoxy resin Company who have baffled me with science and figures. (they denote their products with a letter and figures I.e. A 320) Thought they may be able to come up with a simple solution but when the talk progressed onto Formula one car construction I realised I was a bit out of my depth!
  2. pmdevlin
    Lieutenant
    I feel your pain! I was very reluctant to glassfibre my 3 foot Fireboat when it started delaminating, I was pretty much bullied into it.
    If you have see the pics of the boat finished, then you have evidence of how it turns out. Many people will offer opinions, I'm not saying in any way what I did was the best way, but at least you can see it worked.
    The car repair stuff is specifically for that, much larger jobs, bigger scale. I was very lucky to have someone to virtually do it for me, but I learnt, and did this boat with a lot more confidence, but it took ages to get to the paint, the prep makes the job, the glass cloth as pictured is light, strong, and will protect the wood, just dont do the inside as the wood will not be able to breathe. what ever way you do it, let us know how you get on 👍

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Aerokits 46" fireboat twin screw brushless conversion

Before glassing starts, I needed to change from single screw to twin screw, never had a twin screw boat before, so this is new territory for me, time to enlist some help! so ity was over to HS93'S workshop!
We set on the hull where I wanted the props to be, leaving room for water cooling pickup, and the rudder. I have seen quite a few people make the mistake of having the rudder too close to the end of the hull. What happens then, is the boat almost "pendulums" on the rudder, making a pretty poor handling hull very bad. A circular template was make same diameter as the intended prop, plus a bit extra, then a flat was put on the template, and put on the hull, now we know where the props will be.

Cut a hole for the shafts, and a strengthening plate inside the hull for each shaft. Sounds easy but it took a while to ensure the shafts are equal, straight, and same place on the hull. (I watched during most of this!! 😯 )

Rudders are shop bought, but the rudder tubes are home made from brass, with a o ring to seal, epoxy resined into the hull. Again, a strengthening plate inside the hull to protect the flimsy skin.

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Aerokits 46" twin screw brushless conversion

as you can see I was very lucky with this buy, its in excellent condition, so a lot of the work is already done. I dont do full builds, I seem to specialise with refurbs and rescuing unfinished projects!

I am using a digital servo for rudder control, as these tend to operate faster, and have more torque, it also has metal gears so should be more resilient. I intend to test a gyro after construction, got one ready from a rc helicopter.

For those that are unfamiliar with these, on a heli, a gyro in simple terms keeps the tail in the direction the operator wants, so compensates for any wind that may cause a deviation, the theory is, if wind is affecting the course of the boat, or some water undulations, the gyro will keep it straight on course. These can be turned on and off with the transmitter whilst the boat is in use, so on a windy day, I will easily be able to see if it is doing any good it may be useless, but I like dabbling with things, and these hulls handle bad at the best of times so anything will help!
2 comments

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Aerokits 46" Fireboat twin screw brushless conversion

Fibre glassing......the secret is, go to a friends house, use his workshop, then all the resin drips on his floor!

In all seriousness, on a big boat like this, its a two man job, as the resin goes off quite quick, and the cloth shrinks, pulls, and moves, its a horrible job, but worth doing as the wood is sealed once and for all, but there is a lot of work involved afterwards, sanding finishing etc, this is the cloth that was used.
2 comments
  1. AlanP
    Lieutenant
    Fibre glassing in a mates workshop, that's a good way of getting rid of friends 😁

    I have always had trouble with fibre glassing, goes off too quick, does not go off at all or goes off leaving a sticky coating, can't seem to get the mix right. 😭

    So now I use Z Poxy, the Racing Sparrow (yacht) that I built had a balsa planked hull, on this I used matting with the Z Poxy to give strength. I find Z Poxy is very easy to sand to a good finish with wet and dry, also if you carefully run a heat gun over it, it just about self levels. it works for me anyway 😛

    Alan
  2. pmdevlin
    Lieutenant
    Heat gun is a great idea Alan, I never thought of that. it would have helped 👍

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Aerokits 46" Fireboat twin screw brushless conversion

I need to slow down, or it will get boring, and I will take over the forum 😰

As mentioned previously, we decided that we need to glass the hull, this will make sure the wood does not rot in the future, as we dont know how old the boat actually is.

The hull was a bit of a job, getting the cloth and resin around the shafts and rudder positions, resin applied to the wood, then the cloth over this, then another coat of resin, next is the labourious job of sanding down, couple of pics of the rear of the hull shows the process. its only the second time I have done this, its really horrible to do, but worth it when you come to paint, as the finish is great, but you have to be soooooo patient 😉
1 comment
  1. Dave M
    Vice Admiral
    I have used Epoxy resin with cloth and agree it is difficult to make good on other than flat or gently curved surfaces.
    Polyester layup resin works much better and you can control the setting timescale so you can ensure the cloth and resin are well attached to the hull.
    I usually rub down after the first coat and rework any dodgy looking areas. A thin final coat is then easily prepared for the finish.
    In any case the final result you have achieved looks superb and I look forward to following your progress. 😀

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