M Class NEW PLAN

[Gio]

Hi Gio,
my readings show that some US1 models are ranging around 1.8/2.0kg for the bulb and 2.8/3.0kg as full displacement. 2.0/3.0= 0.66% is a good figure for the righting moment.
On RCgroup it is reported about Hull16 with 1.8kg and 2.77kg full displacement (4lbs/6.12lbs).
I wonder if the 970g left are sufficient for the full contruction. I do not have such experience with US1.
Remember anyhow that volume scaling go with the “cube” of the scale.
You need first to find out what others have done in terms of displacement as such to make your hown decision.
For a US1, you need to draw it from scratch.
ClaudioD

Claudio, I have to admit that your number look much better than mine, my boats tended always to be on the heavy side, plus the conversion from lb to km is still giving me some “issues” after more than 10 years.

As for construction, yes that’s possible with room to spare, USOM tend to be “bare hull” models with little more than the bare necessities, even the deck is now mostly made out of plastic film (monokote).

[slotracer577]

Hi Gio,
my readings show that some US1 models are ranging around 1.8/2.0kg for the bulb and 2.8/3.0kg as full displacement. 2.0/3.0= 0.66% is a good figure for the righting moment.
On RCgroup it is reported about Hull16 with 1.8kg and 2.77kg full displacement (4lbs/6.12lbs).
I wonder if the 970g left are sufficient for the full contruction. I do not have such experience with US1.
Remember anyhow that volume scaling go with the “cube” of the scale.
You need first to find out what others have done in terms of displacement as such to make your hown decision.
For a US1, you need to draw it from scratch.
ClaudioD

970g should be plenty for full construction. My M is 750g ready to sail (hull, radio, rudder) minus the fin and rig. The US1m is a lot smaller and the rig is smaller, so I would expect to come in under 970 minus the keel with ease.

[claudio]

Hi,
yesterday afternoon I tried to put some lines togheter, using previous RG65 Esterel drawings see below.
Of course some refinements and cross checks still to come.

ClaudioD

[Gio]

Wow Claudio, thank you, that looks great.

I was starting to work on something similar too, but in the time you did put “your lines together” I barely managed to decide on the displacement.

I may start building this right away, setting aside the footy (and other more pressing house jobs…), before the garage shop gets closed down for the winter … (temps well below freezing in this neck of the woods).

Thank you again.

Gio

[claudio]

Hi Gio,
Be careful I did not cross checked the shadows vs lines plan.
Since I used only 5 shadows instead of 10 the distance between is doubled almost 200mm.
If you intend to use wood stripes or plywood, be sure that is not suffer some flexibility in case of manual sanding.
The Actual shadows are 1/2 size and represent the finished size, so the “skin” thickness shall be removed before.
To make things simple I add the scale 1:1 shadow in PDF format.

Another important point : the actual displacement does not include the volume of the Appendix like rudder, fin and bulb that shall be added, therefore the final displacement will increase.

At this point you have two solutions, increasing the bulb weight for better righting moment when sailing with heavy winds or let the boat floating higher on the water with smaller bulb when the wind is low. There is still some margin before the waterline lenght start shortening.
Chers
ClaudioD