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[justboatonic]

Howdo. Anyone had this problem with MSW Envoy? The instructions say to drill an 8mm hole where the prop tube exits the hull. Anyone who has an envoy will know that internally, both sides of the hull converge at the stern so there is a very narrow almost valley like form. On the outside, where the prop tube just pops out of the hull, there is plating detail almost saddle shaped on each side.

OK so no one is going to try and drill an 8mm hole straight off. So, I marked off the centre of the boss on the stern where the prop tube would just exit the hull. Got my cordless speed sensitive B&D drill started off with a 2mm bit and drilled from the outside into the hull making sure the drill was along the hull centre line and level. Stepped up the drills from my collection 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6mm to ream out the hole. Each time I let the drill make the hole nice and slow making sure it didnt 'grab' the GF.

Put the 6.5mm drill in the bit and started to drill gently when 'crack'! That didnt sound good  Stopped the drill immediately to see what caused it. Its a bit difficult to explained in words but, it looks like the GF hull has a crack about an inch to an inch and a half starting from where the two halves of the hull join just about on top of the drilled hole down to the 'saddle' plating covering the prop tube.

Seems odd the GF should crack like this when only stepping up half a mill from 6 to 6.5 and based on the instructions, the hole needs to be 8mm! OK the small crack can be fixed with a little GF but, there's no way I want to try and run any more drills through this area. I have a dremel which would allow me to open up the outside hole but the problem then becomes the inside.

Due to the shape of the hull at the stern where the two halves of the hull come together, internally there is a longish very narrow channel. I estimate this to be about 25 to 30 mm in length. It looks less than 8mm wide, probably nearer 6 to 7mm. I dont see how I can get any part of a dremel tool in there to ream the hole out to 8 mm.

How have other builders of the envoy got around this and did you have any problems drilling the prop tube hole?

[FullLeatherJacket]

David
I used a rat-tail file on mine.
FLJ

[justboatonic]

David
I used a rat-tail file on mine.
FLJ

D'oh! Now why didnt I think of that! 

Seems like a plan!

Cheers Dave, Hope you are better 

[FullLeatherJacket]

Cheers Dave, Hope you are better 

I'm working on it, dear old thing!
Back to the model - once you've fitted the tube and aligned the motor and coupling I suggest you fill the 'channel' with Isopon P40 (the stuff with the chopped strands mixed in). That will close up and reinforce the hull around any cracks you may have made in the GRP.
FLJ

[justboatonic]

Er, next 'problem'!

Has anyone fitted a Graupner 900 series to an Envoy!?

Finally got the prop tube inserted after using the dremel and hand file. Trouble is, the prop shaft supplied doesnt line up with the motor when fitted on an 'L' shaped mount. There's a difference of a good inch between the centers of the motor shaft and prop shaft. I cant file the channel for the prop tube much more as the prop itself would be at a silly angle by the look of it. It would also probably cause the prop to foul the rudder pivot if fixed at the angle needed to make the motor and prop shaft line up.

Only option as I could see it would be to use a longer shaft or change the motor to one of those noisey MFA geared jobs which is why I bought the 900 in the first place! If I use a longer shaft, it makes the fitting of batteries (2 x 12v SLA's) more difficult.

Has anyone fitted a 900 and if so, how did this affect the layout of the gear inside the hull?

[Bunkerbarge]

Mine has a Hectaperm geared motor in, which admittedly does make noise but powers the model perfectly.  MFA units should not make noise as they are belt driven.  I think you need to be geared down for a large model and a large prop plus this allows you to align the motor and shaft easier.  I would be very cautious about a 900 directly connected, that sounds way too powerful to me.

If you have an MFA unit play with it on the bench and try to find out why it is noisy and fix it if possible.  If the noise generated by this is too much then you are getting yourself backed into a corner.  You really need a geared motor and they are always going to be noisier than a direct drive.  You could kill the noise by surrounding the motor with sound insulation in some sort of box, as long as overheating doesn't become a problem.

If you can live with the noise my Hectaperm provides scale speed and manoeuvring, comes with the built in gearbox and it's own base for easy mounting, it's also bullet proof and should last forever.  You could then work on reducing the noise if you want afterwards, although I tend not to notice it nowadays unless I'm thinking about it.

[justboatonic]

Mine has a Hectaperm geared motor in, which admittedly does make noise but powers the model perfectly.  MFA units should not make noise as they are belt driven.  I think you need to be geared down for a large model and a large prop plus this allows you to align the motor and shaft easier.  I would be very cautious about a 900 directly connected, that sounds way too powerful to me.

If you have an MFA unit play with it on the bench and try to find out why it is noisy and fix it if possible.  If the noise generated by this is too much then you are getting yourself backed into a corner.  You really need a geared motor and they are always going to be noisier than a direct drive.  You could kill the noise by surrounding the motor with sound insulation in some sort of box, as long as overheating doesn't become a problem.

If you can live with the noise my Hectaperm provides scale speed and manoeuvring, comes with the built in gearbox and it's own base for easy mounting, it's also bullet proof and should last forever.  You could then work on reducing the noise if you want afterwards, although I tend not to notice it nowadays unless I'm thinking about it.

Hi BB. I think you may be thinking of a different MFA geared motor. The MSW recommended one for running off 12v is geared 6:1 (I think) and has metal gears. MSW have said a 900 is OK and they have some available on their site. I guess one has to use a longer shaft with these as there's just no way I can see the motor and prop shaft centers lining up.

Looks like I may have to go back to the original MFA motor 

[Bunkerbarge]

That makes sense.  Have a look around though for a Hectaperm as well.  They are not that common but you do still see them on eBay occassionally.  Yes it makes noise but it is a perfect motor for this model performance wise.

[FullLeatherJacket]

If you have bought a Graupner 900 then remove that big flange thing from it and then sit back and consider fitting the motor without  an L-shaped bracket. I've just had the plan up in AutoCAD and there's theoretically  room as long as you haven't fitted the prop tube any lower than as drawn.
On 12v it will fly! Mine had the specified 12v 6:1 Torpedo and you couldn't hear the noise when the model was more than just a few feet away on the water. The water also seems to deaden the drumming sound, while putting the lid on the hull stops the nasty HF whine of the gears. A light spray-oil inside the red gearbox cover helps, too.
FLJ

[justboatonic]

If you have bought a Graupner 900 then remove that big flange thing from it and then sit back and consider fitting the motor without  an L-shaped bracket. I've just had the plan up in AutoCAD and there's theoretically  room as long as you haven't fitted the prop tube any lower than as drawn.
On 12v it will fly! Mine had the specified 12v 6:1 Torpedo and you couldn't hear the noise when the model was more than just a few feet away on the water. The water also seems to deaden the drumming sound, while putting the lid on the hull stops the nasty HF whine of the gears. A light spray-oil inside the red gearbox cover helps, too.
FLJ

Cheers as always Dave. There's deffo room in the hull. As you know its cavernous. Im assuming if you mean fitting the 900 without a bracket, it needs to be fixed in with sealant of even glass?

[FullLeatherJacket]

Two methods occur to me.

The first is to fit the motor to an L-bracket and screw this to a larger 6-8mm ply plate; this is then screwed 'upside-down' to a pair of longitudinal wooden beams which are glassed into the hull about 50mm each side of the keel line, thereby "hanging" the motor in the space just above the keel and in line with the shaft.

The other would involve some right-angle triangular wedges, carefully carved and P40'd into the bottom of the hull each side of the motor. The motor is then held in the 'cradle' formed by these wedges with a couple of tie-wraps or other straps across the top of the motor.

The third ( ) would be a transverse 8mm ply bulkhead glassed into the hull at the position of the motor fixing screws, and just tall enough to accommodate the height of the motor. Screw the motor to this with the shaft passing through it (with just the same hole pattern as a metal bracket); align the shaft and coupling and glass the bulkhead in place. You'd need a shape-tracer to get the section right but it would probably be less work than the other two methods.

As you say, you could even just sit it down into a bed of sealant, but you'd need something to hold it firm and stop it rotating.

FLJ

[HS93 (RIP)]

two things, the first is B+Q do a file for sharpening chain saws , they are about 1/4 dia smooth cut but the main thing is they are parallel oh and very cheap I got one a few years ago and it is very handy there is about 10" of cutting available are so are handy when altering the angle on old wood hulls as well.

the other thing is I helped someone with the same type of problem  (different boat) and we used MFA belt drive gears, both the same size, but could be altered to give more power not req in this case. they are very quiet. the metal geared MFA boxes in my view are very noisy.Duval have the same belts and gears as well.

Peter