Making a new Yacht

Hi everyone,
I’m in Yr 12 this year & for one of my subjects I’m making a R/C yacht, I have a hull for a 10 Rater so I thought I would use that, but I don’t want to make the it to the 10 Rater rule.
I have been sailing my dads 10 Rater for a couple of years now, in between sailing & teaching people how to sail.
The length of the hull is like 1.54m, beam is about 31cm, the mast of dads is 2.22m high, so I was thinking if I increase that to 3m, but I don’t know how to work out how bigger I will need to make the bulb and keel.
Plus I was thinking of adding a assy kite like on the 18ft skiffs, but I don’t know how to do that as I’m new to building RC yachts.
Thanks in advance

Download Attachment: Rcyacht.jpg

You’d take advice from those whom you call idiots?

The other Matt

I think it would be a big mistake to increase the rig to 3 meters! You’d do better to change the planform of the sails -at least the main -to a square top keeping the CE as low as possible. Some 10 raters in the US are experimenting with square tops with good results.
On there are sketches of two different spinnaker systems. On a model an asy spin is exactly TWICE as costly and complex as is a symetrical spinnaker. On an asy set up you need one or two powerfull sheetwinches in addition to the set/douse winch.
To add an asy and have it effective you would need to plan on a retactable bowsprit about 20% of the length of the boat or a shorter wagging pole. Also , the jib area may have to be reduced in order to prevent the jib from blanketing the spinnaker.Since you can’t just reduce jib area without affecting the balance of the boat you’ll have to analyze how much to reduce the jib and how much the increase in the main will require you to move the the mast forward-and then do you have the room forward for the spinnaker trough(hole). You simply can’t just add a spinnaker to a model without considering these factors.If you’re serious I can help you understand thisbetter with comparisons to the Spinnaker 50 and America One- both of which have been racing for years with 100% effective spinnaker systems.
To use either system you will need a 2.5"(64mm) hole in the deck just forward of the forestay leading to the same diameter tube inside the hull. You’ll need at least one drain right at the hole.
The tube inside the hull shuld be sealed and be half the hoist long plus 50mm or so.
On a model because of the loss of pitch stabilitity compared to a full size boat extreme care has to be used in deciding what size spinnaker to use. You can set it up to have multiple spinnakers for different wind conditions or a single allround sail but the sail you use for winds over about 7 knots should be designed to lift or else the boat will pitchpole immediately. With the proper angle and a lifting spinnaker you can carry the sail in the strongest of winds. See the topic on “rc spinnakers” as well as the topic on “Spinnaker 50 Design Considerations” (both under “Technology”) for help in understanding how to set up a spinnaker.

Doug Lord
–High Technology Sailing/Racing

How did the boat sail with the keel and sails you have now. What is the draught and bulb weight, actual sail area. What are the wind conditions.

you make my day

I tell you what you could try, take a look at this boat for an idea; You could try somthing along those lines, if the hull isnt too heavy. Go for a lower aspect rig with a square top, lose some of the lead. As for a kite Dougs the man to talk to, An assymetric would be fun [;)]

Luff 'em & leave 'em.

Hey greg, just an idea, somthing like a narrow sportsboat might work, lighter displacement with a slightly smaller rig, just suggesting that perhaps adding more sail area and ballast isn’t the best way to make the boat actually go faster, all your doing after all by making the boat heavyer is increasing wetted area and making the boat more stuck in its hullspeed. Just a thought OK?!

Luff 'em & leave 'em.

I wouldn’t sell you the 10R cause it is my dads, I got a hull cause we got the mould for it and at least those who i called idiots help me when they are being nice, when they are attacking each other & every one else thats when i think they are idiots cause they aren’t helping any one just going on about how my boat goes faster & all that other shit!

Wow - and an attitude to go with it ![:(!]

If you have issues - take it up specifically with the person (or persons) - don’t try to paint the entire board with just one stroke of your juvenile brush.

Matt White, how do you know i take advice from idiots? After talking to Matt Lingley, I have realised that Doug isn’t as bad as you all make him look. Now I take a lot of what I thought of Doug back cause at least he helped me, so far only Doug & Matt have advised me, so how can i take any advise from any one else if no one else has given me any advice?

got to ask for the advise first. duhhhhhhhhhhhh


have you read the first post, or do I need to say “I NEED ADVISE,” I said “i don’t know how much bigger to make the keel & bulb” so now I realise that for other people I need to say “I NEED ADVISE”. Doug & Matt started giving me advice. So Now I ask for ADVISE, will anyone else advise me as to what is the best way to build my rc boat.

And as another reply to Greg this is what he put in his reply to my post
“Why would you think of bastardizing such a class boat.”
I’m not bastardizing such a class boat. I used the measurments from dads boat because it is the same hull, mines only like .5cm longer, so I am using his boat for mearsurments, I am not changing anything on dads boat, I AM BUILDING MY OWN.

Rob: Things can get a little confusing here, I think some of the people thought you wanted to rebuild your Dad’s boat, not build another one from a similar hull.

The first person you should really talk to is your Dad. Building a fin and bulb usually involves working with some pretty toxic stuff. And spinnakers for r/c boats are pretty rare (some would even say experimental), at the very least it will be complicated and maybe expensive. The important thing will be to have someone with you with experience to help out. So check out with your Dad what direction he thinks you should be going in and how much time he has to work with you on the project. If not your Dad, maybe some of the other designer/builders who are around and have experience with 10Rs can be of help. I know Brad Gibson (who just won the Australia 10R Nationals) and I feel pretty sure if you asked him the right way he would be glad to give you some advice.

One thought is to just build your hull up conventionally to start with. Frankly, building an r/c boat even from a kit is quite an accomplishment. Putting on the deck, setting up the sheeting system, getting a good finish and building a rig would be pretty impressive in and of itself. A lot of us still can’t get it right and we’ve been at it for years.

Good luck.

As far as I know; nobody said Doug is an idiot!!!
you should read the post carefully before saying out loud something…wrong
and people call me childish LOL


if it isn’t broken, don’t fix it!


What I meant by idiots is that they are always arguing about whos boat is better, which is what I think is idiotic behaviour.


Do you know where Brad lives? & if he lives in Victoria do you have his phone number?
I don’t think I’ll end up setting up the kite as the more I read about it the more comlicated it gets, that can come later if it wants. I can get a lot of the materials because I sail with a sailmaker, I have a couple of friends who are riggers, I have a mate who is an engineer, I have a family friend who works for MotorSpray (makes resins & car stuff)& also have a friend who I used to sail with who is a Naval Architect. But I don’t have many friends who are experienced in RC yachts which sucks.
And my boat is only longer because of the mould that has a flat bit at the stern so that will probably get cut off.
I was thinking about making a rig like the 18’ skiffs, they have flexi-top rigs but that would be pretty hard to make.

Thank you for helping me.

The only way to sail is to have FUN

I just love to be “childish”[:D]

“Idiot=a mentally handicapped person”

not from me…check for yourself

As far as I know, none of them are like this!

and yes I am childish[:-clown][:-devil]

if it isn’t broken, don’t fix it!

The Brad that you refer to I take it is Brad Gibson. If so get back to me and I will give you his e-mail address if you don’t have it. He lives in N.S.W.

Hey Rob…

I was struck by the fact that within about 10 minutes you posted the “we are all idiots” message, then asked for the advise. It would not have been so bad if you had not used the broad brush, as Dick says. An example of the inaccuracy is your assumption that I have been on Doug’s case.

Anyways - enough about that - I hope you have some luck with the 10R project. There are lots of people here that can offer good advise.

The Other Matt

Hi Peter,
Can you please send me Brad’s email as it would cost to much to phone him as it is STD rates(I’m in Vic, he’s in NSW)
thank you very much.

Matt, I’m sorry about that, I won’t post any more negative posts.

Everybody else, I am asking for advise.
If I were to do as Doug advised me to do & increase the sail area by making a square top, or what ever else you want to call it, could I increase the mast height to about 2.3 maybe 2.4 from 2.2?
I’m also thinking about instead of increasing the weight of the bulb maybe increase the depth of the keel, but don’t know how much, the current depth of the keel is 40cm from where it joins the hull to where it joins the keel.
How do you calculate how much sail area there is?
If I was to increase the sail area would I have to increase the rudder size?

thanks to everyone who helps me.

here you go:


if it isn’t broken, don’t fix it!