help needed

[david the newbeParticipant @davidthenewbe]

hi all

im doing my first ever scratch build form plans of a narrow boat

pics of plans below

i have cut out the main hull ready to put together

but the prob i have now is the bit at the back bottom half needs to bend round a bit and im not sure how to do this any help would be most appreciated

thanks dave

[david the newbeParticipant @davidthenewbe]

need info on bending plywood

[Bob Abell 2Participant @bobabell2]

Hello Newbie

I would use very thin ply about 0.030" thick…….(1/32&quot

For the bend at the rear, ensure that the grain is vertical and try bending first round a tin of paint or similar, very carefully and slowly.

You could do it in stages and gradually reduce the radius

Bob

[Paul TParticipant @pault84577]

Hello Dave

If you have access to a wallpaper steamer or some other kind of low pressure steam generator then you could make yourself a small steam chest and use that to bend the plywood.

Paul

[Bob Abell 2Participant @bobabell2]

Can plywood be steam bent?

What about the glue?

Bob

[Paul TParticipant @pault84577]

Bob

Most ply is wsb (water, steam and boil proof) but small sections can be steam bent quite easily.

[Gareth JonesParticipant @garethjones79649]

I would go along with Bob's suggestion to bend the ply around a former such as a tin or piece of tubing. The grain needs to be vertical so that you are bending it in the most pliable direction. You will find that the strip will tend to try and straighten out afterwards so gradually reduce the radius of curvature in stages with the final one being somewhat tighter than you require on the hull. Leave the material clamped or strapped on the former overnight to take up a permanent curved shape.

I would try and arrange for there to be a straight section on each end of your formed piece with the joint for the hull sides somewhere along its length. That way you have a bit of tolerance and spare material to play with when you join the sides with the end piece. I think its easier to make the joint in a flat area rather than trying to join a curved and a flat piece together.

!/32 might be a bit thin for the hull plating so you may need to make two pieces and laminate them together. If you make the outer sheet longer than the inner it would be possible to stagger the joints with the hull sides and get a stronger assembly.

I have steamed small pieces of ply sheet quite successfully in a kettle but I would not think it would be necessary for a fairly gentle curve like the back end of a narrow boat.

Gareth

[Bob Abell 2Participant @bobabell2]

The rear end could Also be created by the plank on frame method?

Bob

[david the newbeParticipant @davidthenewbe]

thanky you guys

i think ill try bobs and gareths suggestion or may just use balsa .

as i will have to cut that bit of as on the plans its all on that 1 plank and thay said to use 3.5mm ply.

wot sort of glue should i use as the only kits i have biult are aerofix kits

[ashley needhamParticipant @ashleyneedham69188]

David. PVA would be my choice. Will not be other persons choices but there we are. Glynn Guest uses PVA so if its good enough for him..just seal the hull well with sanding sealer, dope or varnish and you will not have a problem. My sub is glued together with PVA…

Bob`s subbestion of the plank-on -frame method has much going for it on such a small section. Simply cut two sections of the correct radius, glue them top and bottom. then use thin vertical planks of balsa or ply to build around the stern.. I assume thats what you meant Bob? will need a bit of sanding and possibly filling and hey presto. This method may be more accurate than the other, depending on your luck, well, its luck with me!

Ashley

[Colin BishopModerator @colinbishop34627]

You won't be able to bend 3.5mm ply! Not easily anyhow.

For bonding wood, use an Aliphatic glue (yellow stuff). It is effectively waterproof but you will need to clamp the components together while it sets which is overnight.

Colin

[Gareth JonesParticipant @garethjones79649]

David

3.5 mm ply is a bit thick to bend without steaming unless the curve is very gentle. I would recommend several laminations of 1/32 sheet (0.75 mm thick).

I would use an aliphatic resin adhesive. You could use a waterproof PVA adhesive if you have some already, but I find the aliphatic resin 'grabs' more quickly and bonds in less time.

Gareth

[david the newbeParticipant @davidthenewbe]

thanks again guys

looks like ill try several sheets of 1/32

as for the glue i think ill go for the aliphatic resin as its a little bit better then PVA for sanding and painting on

thanks again dave

PS i will post same pics as i go a long

[Colin BishopModerator @colinbishop34627]

Yes, keep us informed and don't hesitate to ask for advice if you get stuck (in all senses of the word!)

Colin

[david the newbeParticipant @davidthenewbe]

hi guy

a few weeks down the line and i have a few pics for u of my first build

and 1 with 1 of the side for the cab

just takeing my time and its starting to look like a narrow boat

any ideas on size of prop shaft i should use im looking at useing a 25mm prop and maybe a mfa 540 motor running of 7.4V

dave

Edited By david the newbe on 09/10/2012 14:56:04

[ashley needhamParticipant @ashleyneedham69188]

David. Looking good so far. This sort of ply will need sealing (I use sanding sealer) and then probably 3 coats of ordinary undercoat rubbed down well between coats, to hide the grain for a smooth finish (when you get to that stage of course). I like 4mm ply, have built several things out of it.

35mm prop probably a better size for this boat. or it will struggle to move.

MFA 540 will be ok on this size prop at 7.2V. Did you mean size of propshaft..or prop?? A 4mm shaft of sufficient size to connect motor and prop is the thing. BY THIS I mean decide where the motor and prop are positioned then see how long a shaft you want. Allow room for a coupling of course.

Marks model bits do stainless shafts and rubber couplings that are reasonably priced, and should run silently, essential for a narrow boat, unless you have a radio in it!

Ashley

Edited By ashley needham on 09/10/2012 18:28:55

[LARRY WHETTONParticipant @larrywhetton68737]

 

  

nice build so far,  my stern is balsa shaped toa template  shaft and rudder tube inserted

 all woodwork ikea blind

Edited By LARRY WHETTON boatman76 on 09/10/2012 20:07:52

Edited By LARRY WHETTON boatman76 on 09/10/2012 20:32:10

[LARRY WHETTONParticipant @larrywhetton68737]

Few pictures of build……and lay out of work boat , hope this helps Larry….

[david the newbeParticipant @davidthenewbe]

hi guys

and thanks for the advice and thanks ashley for the advice on sealing the boat i will get some sanding sealer tomorrow along with some brass to make the rudder as i cant find some where that sells rudder for the size of my norrow boat.

dave

[ashley needhamParticipant @ashleyneedham69188]

Dave. Dont forget the filler!!! seal the ply first with the sanding sealer and then apply p38 car filler (or whatever). Dont be shy. Use knifing putty or the stuff sold in small tubes in modelling shops AFTER the undercoat, as any blemishes will show up then.

All this before doing the detailing.

Rudder.. I like to use the nylon rudder tillers. they take. I think, 5mm brass rod. Easy to get brass tube to fit over this, cust a slot in the 5mm rod and solder in a bit ofthin brass sheet… instant rudder. The nylon tillers enable you uto set the rudder after trials very easily, I replace the standard nut and bolt with a longer bolt and nyloc nut to retain the grip.

Ashley

[LARRY WHETTONParticipant @larrywhetton68737]

 

 

Hello David ,

Have look at the rudder detial here , better for turning,

will try put sketch together to show to do it quite easy to do , using brass and tube ….

 

larry…

 

 

 

 

 

 

 

 

 

 

Edited By LARRY WHETTON boatman76 on 10/10/2012 09:54:53

[LARRY WHETTONParticipant @larrywhetton68737]

Hello Dave,

sketch of rudder detail iuse on my narrow boat hope this helps ,

post if not sure ……Larry…

[david the newbeParticipant @davidthenewbe]

hi larry and thank you for the sketch most helpfull

thanks again dave

[LARRY WHETTONParticipant @larrywhetton68737]

HI DAVE ,

Whose plan are you using?…………..Larry..

[david the newbeParticipant @davidthenewbe]

hi larry

i got the plans from **LINK** as it was the only plan for a norrow boat i could find its on a A1 sheet and cost £11.

dave

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