I agree the wrap around screen is not easy. My one nestles in a deep groove on the upper edges of the cabin sides where it is cemented in place.
As I said I had to replace it and delayed as I did not fancy the job, so when I eventually came to it the glue had failed and came away as crystaline particles.
It is getting the fit over the curved roof which is a slow fittting job.

At my scale the window frames were impossible and mine are thick paint.
I carefully masked everything and then about 6 or more coats of paint and leave to dry for several days.

I know planked decks are nice but of the several I saw they had a canvas deck so I just painted them as per.

Now I have her running I can see that there is a small take up of water, probably spray, I will have a think about that!

Roy

Right I have some data for you. First thing is she planes nicely. But not until I moved the drive battery 20mm back.

The power needed was 19.25 Watts. Measured under load and my guess would have been 20 Watts.
The beam is 13cm.
The amount of hull in the water when planing is 25cm.
LOA 40cms,
However, the deep vee surface is a bit over 14cms. (7cms each side including 3mm spray strip)
The weight is 791 grams or 1lb. 12 ounces.

I used a powerful 380 geared down 1:2 on a 35mm diam plain plastic 2 blade prop.
This motor is rated at 40 Watts so does not get hot. In fact when first planing I had an X prop and I changed down to the P pitch and she went a little faster.

The battery is a home constructed 6 cell 4/5th sub C, 2800mAhrs 6 cell battery welded together. When charged it has about 20Watt,Hour capacity.
Next time out I will check on endurance time.

Anyone with any formulas on planing and weight and surface area perhaps they fit in with theory?
Regards
Roy

Thanks for the information Roy. I thought I'd got most, if not all of them covered but you never know.

I've got the windscreens and pulpit rails to do which I'm a bit apprehensive about, but having said that, I was about other things, like the planked decks, but they turned out OK in the end.

Like most builders I've gone for single props as well and would have liked to do a twin. My Swordsman would have been a good candidate as it's got plenty of room but as it was only my second build I wasn't ready to tackle that then. I could modify it but the build has taken too long as it is, being left for long periods of time, and so I'd like to get in finished as it is.

Chris

Hi Chris the Sparkler was a free plan from possibly the RCME magazine I think the Bobby was a later and slightly larger derivative.

The superstructure was constructed from a side photograph and constructed of thin 1mm ply. The difficult bit was creating the wrap around screen, lots of cereal packets on a trial and error basis. the sides have a double thickness with slots left for the screen to be retained.

What would be the framing in metal of the screen is simulated with several layers of white paint with the screen having masking tape for the shaping.

The handrails are quite strong as they are soldered tubing supported by slightly flattened oval shape tubing and etched and painted to resemble wood. The pullpit has been damaged several times but is soldered tubing and brass hard wire and small washers at the base and aluminium paint.

It is over 40 years old now but has survived well. The spray rails are a little exaggerated but do the job.

So not a kit, just a one-off model. I think it works out to 1 : 24 scale, sort of looking for crew as well.
Back when building our son was with me and we found the full size boat moored up and after a little conversation we were invited on board and if I remember correctly this was the colour scheme.
I liked it so used it. By the way the couple had hired the boat for a week.

It was some time after I realised the Huntsman had 2 props, if I had known it would have had 2 props, bit annoying that!
Roy

Hi Roy

So it was essentially a Sparkler, which I believe was one of Vic Smeeds designs and you modified the superstructure?

I hope you don't mind me asking but I've written something on all the Fairey drawings and kits I know about and a 16" Huntsman 31 from the 1980s isn't one I knew about.

Chris

Hi Chris thanks for the mention. My Huntsman is essentailly a Sparkler hull from way back I had a powerful 380 with a 2 : 1 reduction gearbox and an old 6 volt camera battery driving. It planed no problem and as I said barely controllable.

I have been trying to make it plane but not go as fast but this has become the sticking point.
I have some lighter 7.2 volt batteries 4/5th sub-C, and I shall be trying these also an esc that weighs about an ounce. Fairly soon I would think. Will keep all informed and if it works I will send a picture.

The battery pack I have, I made myself as I recently bought a mini welder and nickel strip and 2800mAhr cells.
Roy

Roy - the plot thickens or at least changes! I had a look in Your Harbour and I see it's a Huntsman 31 and only 16" long. You made a lovely job of it for such a small model though.

Total conjecture here, but you know with some models you have to increase the beam or freeboard to make them perform satisfactorily and I think your model might be suffering because of its small size? The Huntsman 31 has a quite long narrow hull with a deep vee and not very supportive bow. Whilst it is a planing hull, but being a deep vee rather than flat it will never plane at a particularly low speed. My Huntress is quite beamy for its length and a shallower vee but is still going quite fast when planing. I doubt you could reduce the weight by much and doubt it would make much difference anyway? Spray rails might make a difference? I mentioned in my previous post that they can suffer from a bow down attitude and I've read of some folks having handling problems with the boat flopping into turns like PT boats are prone to.

Chris

Talking of weight, out of interest I weighed the model of the Fairey Huntress that Dave Milbourn built and it came to 1186g plus the battery giving 1409g. Full size weighs around 2500kg which for 1:12 gives a scale weight of 1446g (2500/(12x12x12)) which I found surprisingly close given that the full-size has a heavy diesel engine etc. The weight distribution would be completely different though with the motor sat further back and with fuel tanks and freshwater tanks etc.

I assume that the scale weight is calculated in the way that it is so that the model sits on the waterline? And allows for the fact that water isn't to scale and so offers more buoyancy?

When working I used to do structural calculations (steel and timber) for building works but wouldn't contemplate doing any for boats, and especially models, as I can see so many complications, especially from the positioning of the motor, battery and RC equipment etc. and the shape of the hull and would do others do and arrive at an answer by trial and error.

Myself and ToraDog did make contrasting posts but that was more from me being lucky to some extent with my models sitting on the waterline due, as I said, to the buoyancy of the hulls because of their size and weight. So with those, no trial and error involved as they sat as they should from the off! I haven't tried my Huntsman 31 yet, as I need to get some paint on it, but I think I may have a slight problem with that as they tend to sit bow down a bit due to the design of the bow and so I may have to put some ballast in the stern.

ToraDog was correct in saying that CofG is important but I still think that with planing model boats (unless very small or marginally powered) that the overall weight, (as I said within reason) is less so. I don't think that building light or heavy will really make that much difference?

Dave M. built his models light by using Liteply (I'm not a fan of it) and I build heavier using birch ply and thicker frames etc. Be interesting to see what my Huntress stern-drive model weighs?

Roy's Huntress should have no problem getting on the plane and I think it's due to lack of power/ too low a revs rather than weight. Spray rails/strakes do provide lift but that is more important on full-size boats that don't have such a good power to weight ratio and a need to be more fuel efficient. My Club 500 doesn't have any and gets onto the plane easily with it's brushed motor.

Hi Roy,
Re: PS I think Billions of Yen is not all that much!! Last time I looked it was 147 to the GBP.

I wouldn't sniff at 1/147 of a billion Yen = 6.8 Million quid or €6.01 million😮😋🤑
So if you have a few billion ¥ lying around ... 😁

BTW At today's rate ¥1.000.000.000 = 5.120.260GBP. Exchange rate 195.
😎

Chacun à son goût Alessandro.
(Ognuno secondo il proprio gusto).
I'm too impatient to mess around with hypotheticals and number crunching just to be able to prove myself right.
I want practical results and ASAP!😁
Ciao, Doug😎