Returning modeller

[Chris FellowsParticipant @chrisfellows72943]

Hi Jim

I'm using a 450mm long M4 prop shaft in one of my builds. It's a Raboesch maintenance free with a ballrace bearing at the motor end and Delrin at the other.

Raboesch make good quality stuff and I've gone with it based on if they make it, it should be Ok. They do 10k. and 15k. versions and as your boat will be revving much lower than this you shouldn't have a problem.

I haven't had my boat on the water yet though. They do an M5 as well which I'm going to use in another build.

Chris

[James Hill 5Participant @jameshill5]

Hi Chris,

I`ve been looking at their web site while generally just looking at prop shafts. I agree , it looks good quality.

I shall be sticking with 4mm shafts this time as the shaft/ props etc seem to be more common giving, a wider choice.

As I said to Chris, once I`m happy with the framework of the hull, and before anything is glued together, then I`ll measure the length shaft I need and see how it goes.

You`re right, with the motors I`ve been looking at, big revs won`t be happening. Just enough to make it look decent on the water.

Many thanks,

Jim.

[Ray Wood 3Participant @raywood3]

Hi Jim,

The amount of keel you currently have inside the hull is dictating the long prop shaft, as you have a deep keel outside the hull, you could cut out quite alot and drop the motor and have a much shorter shaft.If your going twin screws I'd put the shafts & motors in before you plank the hull, cutting out bulkhead later is pretty hard 🙊

Regards Ray

[James Hill 5Participant @jameshill5]

Hi Ray,

I haven`t touched the top of the keel yet. How it is at the minute is how I cut it out so there will be a certain amount of reduction as things move along. I want to get the motors first to try out positioning, then I should have an idea of shaft length.

I`d had a thought on fixing the motors to a common platform across the hull. Might be easier to set angles up for shaft alignment. Will think about it nearer the time. I was wondering about the right time to fit motors and shafts and you`ve suggested before planking, my own thinking had been after, with all bulkhead and any other cutouts done but I`m quite open to be directed differently. You , and others have far more experience than me.

Still fiddling with stringers,

Thanks for your suggestions, good to hear from you,

Jim.

[James Hill 5Participant @jameshill5]

[James Hill 5Participant @jameshill5]

A couple of pictures added showing approximate position of the two motors.

I`ve been looking at different motors and quite like the Mtroniks M600. Originally looked at the 500 but the 600 give a few more revs. ( I`ve used toilet roll holders as dummy motors. )

Now things need to be marked out for cutting some of the keel out. At the moment my idea is to cut down to match the height of the stringer so that maybe I can make a single platform to anchor both motors and their mounting brackets. It`s very much a thought just now.

Prop shaft length looks to be around 15"/16" long depending on where the final prop position is. I`d love to know what the shaft centres were but I can`t find any information. I`m going on the position of the rudders in relation to the curve of the hull at the transom , from photo`s.

Has anyone a suggestion on battery size? ( thinking about the weight ) The only battery I have at the moment is the 9.6v 5000ah for Surfury and that is quite heavy. The real boat only had a 3ft 6" draft so my thought is it wouldn`t take too much to get it to the waterline but I might be wrong.

Jim.

[Ray Wood 3Participant @raywood3]

Hi Jim,

I don't think battery weight will be an issue as she is a displacement hull at the stern, which is where I'd put the batteries, nice to see a dry run like that, it gives you a chance to cut out a lot of weight from the bulkheads, what are you going to plank with ??

Regards Ray

[James Hill 5Participant @jameshill5]

Hi Ray,

Batteries at the stern was my thought as well. It would make it sit naturally in the water.

With this dry run I can get some idea of how much to cut out and from the best places.

I`m going to use the 1/16" marine ply that I have here and double diagonal plank for as much as I can. A lot of cutting out making planks ahead!!

My only problem at the moment is that the hull starts as a double chine at the bow and changes to a round bilge from mid boat to the stern, something I`ve not tackled before.To me that means I may have to plank differently at the bow end. Possibly plank at a different angle, we`ll see.

Ray , a few blogs back you asked what the boat would look like. During trying to find pictures , I Googled, " The Pilot boat Vanquisher" and found very nice,17minute video of it on it`s last trip from The Camber at Portsmouth to Port Solent on it`s way to Africa. The superstructure in the film is white but I shall paint it orange, as I used to see it. What also was useful in the film was the amount of detail to be seen. A bit of a bonus. This is going to be quite a project for me and using two motors will be a first. I`m afraid I shall be asking a lot more questions soon.

Regards,

Jim.

[James Hill 5Participant @jameshill5]

[James Hill 5Participant @jameshill5]

Hi,

A couple of pictures of slow progress this week. ( Why they loaded this way I don`t know, they were taken in landscape ).

One showing the approximate position of prop shaft , coupling and motor. The other picture is a picture of the stern of the boat I`m trying to build.

I`m going to make a card or plastic dummy rudders to work out the size and position of the rudder and the posts and servo position. Also got work out how make some sort of linkage to get them to work together. ( Not something I`ve done before ).

All but the last two bulkheads are glued in place. Need to check wether to cut anymore out of the middle of them. None of the stringers are glued in yet as I need to find a way of holding things down when it`s turned up the other way for fitting the stringers and then the planking. A bit of a puzzle

Once again, sorry about the pictures,

Jim.

[Dave Cooper 6Participant @davecooper6]

Hi Jim

I've not used a twin rudder set-up myself, but, the way I've seen others do it is to couple them together using an adjustable linkage – a threaded rod with ball links (or similar), to allow for them to be aligned. This linkage spans the two cranks at the top of each rudder post.

The steering servo then moves one rudder (via the same crank arm as above) then the other rudder will move in unison.

You can adjust the relative movement 'gearing' (servo-to-rudder) by choosing the appropriate holes on the two crank arms.

I expect one of the others will have a photo of this as the mechanism is really simple once seen.

Regards,

Dave C

[James Hill 5Participant @jameshill5]

Hi Dave,

Thank you for that information. I`m quite a long way from that point at the moment but am thinking ahead as to how it could be made so what you`ve said is very helpful.

Half the fun of this hobby is overcoming something not tried before, with valuable help from others.

Many thanks,

Jim.

[Ray Wood 3Participant @raywood3]

Hi Jim,

Twin rudders are not that difficult to arrange as long as they are not to far back, here's the twin set up from odds and ends such as brass pins from 13amp plugs, a favourite of mine which already has the grub screw fitted with some thin brass arms soldered on a as tillers, some 1/16 brass rod and your in business

Regards Ray

[James Hill 5Participant @jameshill5]

Hi Ray,

Thank you for the picture. Funnily enough ,I came across another picture of yours showing a similar set up while I was mooching through different places looking for information last night. I like the use of the pins from the plugs and I`ve got plenty of those in the garage!

It certainly looks a fairly easy setup to construct so I shall certainly give it a go. I`m going to make a card template of the rudder ( don`t have any measurements to go on so it will be by mark one eyeball from my picture ) to give me an idea of positioning.

Regards, Jim.

[James Hill 5Participant @jameshill5]

Now that I`ve managed to fit all the stringers in, I`ve been looking at the best way to plank the hull.

I said in an earlier blog that I was considering double diagonal planking. Having rough tested some strips to see how they would lay, I`m not so sure. there seems to be quite a degree of twisting going on which doesn`t allow a plank to sit well. It tends to give a raised edge.

My problem is, although I`ve double planked a hull before, I`ve not done one where the chine of the bow changes to the round bilge of the stern. I don`t want to loose the shape at the bow and therefore I`m still looking at planking vertically, overlapping the joins on the second layer, but I don`t know if this is good practice, or not worth looking at.

I wondered if anyone with more experience than me could advise. Perhaps a roller to aid the curvature might help. I`m using 1/16" ply so its quite stiff once cut to a suitable length.

Many thanks,

Jim.

[Ray Wood 3Participant @raywood3]

Hi Jim,

I think the 1/16" ply is basically too thick and as you say won't bend enough and to make the hull a double thickness is a bit OTT ! My MTB is double 1/64" ply, which is about the same price as Gold Leaf these days and White Marlin was 2 layers of 1/32".

The point where the hull transitions from single chine to round bilge you have to establish I guess?

My experience of vertical planking it always looks like a thrupenney bit , you never lose the joints.

If I were building her I'd use a decent quality card for the double diagonal planks and epoxy/glass cloth inside and out. ( just an Idea )

Regards Ray

Edited By Ray Wood 2 on 10/11/2020 16:51:25

[James Hill 5Participant @jameshill5]

Hi Ray, I thought you`d give me an answer. I was trying to be a bit of a miser as I`ve got two good sheets of ply I could use, but maybe not.

I`ve got some card in the garage so I`ll cut a few strips and experiment.

The glass cloth method would be totally new to me so I would certainly be asking more questions. I believe DeLuxe do glass cloth. Seen it somewhere when checking their website for railway stuff.

Thanks as always for your advice,

Jim.

[James Hill 5Participant @jameshill5]

Asking the question , " Has anyone had any dealings with the prop shop recently?"

I put in an order in early September knowing their delivery time was usually 4 to 6 weeks , which was fine. The payment was taken but since then I`ve not heard anything. Obviously my hope is that they have so much work on that there is an obvious delay but I sent an e-mail over a week ago with just a general enquiry, with no reply.

I just wondered if anyone else might know something. I`m not complaining , just curious. .

Cheers,

Jim.

[Chris FellowsParticipant @chrisfellows72943]

Jim

I did read on another forum that he is very busy. Having said that, it is now a long time since you ordered.

Chris

[James Hill 5Participant @jameshill5]

Chris,

Thanks for that. If he`s busy, then that`s fine by me. I know props are made as orders come in so I`m probably well down the line.

I had wondered if the bug had affected his work load but now I know he`s busy I`ll wait my turn.

Cheers,

Jim.

[Dave Cooper 6Participant @davecooper6]

Hi Jim

Coming back to your planking – I used a mix of 1/64 and 1/32 ply on my little RAF launch.

When used as a 'double-biax' – that is an "X" lamination with a good quality glue – it is massively strong. (It's how they made the full-size 70 foot launches after all).

Ray's glassing suggestion is well worth considering though as this makes the whole hull much more 'ding-proof'.

Regards,

Dave C

[James Hill 5Participant @jameshill5]

Hi Dave, thank you for your suggestion.

I tried the card suggestion by Ray but found some of the gaps between stringers rather large, so to maintain the curve I went back to the method I used on Surfury, which was diagonal planking using the ply that I had. I know it`s a bit ott but as I had it I thought I might as well use it. As before, there will be a lot of filling and sanding down before the second layer goes on. I cut the planks 7mm wide as this seemed to be laying resonably well over the hull shape at 45 deg so there`s a lot more to put on yet. When I can get out in the garage I manage to put 4 to 6 planks in total at a time. I`ve used Gorrilla glue this time. I don`t know how this meets with your suggestion of a quality glue? Last time I used Cascamite.

I won`t have enough wood at present do the second layer so will need to order some more shortly. The one benefit I see in a thicker planking is it gives more of a chance of ironing out any blemishes, and I`ll have plenty of those!.

I`ll stick a couple of pictures on the album to give you a laugh at the effort so far.

Cheers,

Jim.

[Dave Cooper 6Participant @davecooper6]

Hi Jim

Regarding the glue – I've not tried "Gorilla" myself but have heard good things about it – particularly strength-wise.

My personal favourite wood glue is "Tightbond Original". There may have to be some additional hull water-proofing (I used sanding sealer followed by model aircraft 'dope', then aerosol paint&nbsp. So far, no leak problems despite the inevitable beginner's crashes !

Do a good float test in the bath /pool before going to big water. I also used 2-pack epoxy where the prop shaft and rudder post penetrates the hull (inside and out).

Good luck,

Dave C

[Ray Wood 3Participant @raywood3]

Hi Jim,

Yes the Gorilla Wood Glue works for me (not the foaming stuff) it dries clear and it's relatively cheap in Wilkinson's

Where your hull goes to single chine at the bow the planking should get easier in 2 lengths ?

I bought a tub of Cascamite from Axminster Tools a while back because we used it at school back in the 60's but I think it was always rather brittle? never got round to using it, Aerolite 306 is the best boat building glue in my experience with the acid hardener But West Systems epoxy has taken over these days.

Regards Ray

[James Hill 5Participant @jameshill5]

Hi Dave and Ray,

I`ve found the Gorilla works well as well. I must admit I`ve not tried the other glues you both mentioned as I certainly haven`t been building boats that regularly.

Epoxy will certainly be used to seal round the prop shafts when the time comes.

When it comes to sanding and sealing, if something like P38 filler or similar is used, is there one adhesive that sticks to any filler that`s exposed better than another? I know it might sound a bit picky but it would be a blow if planks started to come adrift because they hadn`t stuck down properly.

As usual, thanks for your help,

Jim.

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