New .21 outrigger

[MitjaJ]

I'm going to build my first nitro outrigger - I'm total newbe to nitro engines.

Here is the plan:

http://shrani.si/f/24/dQ/1Unstjva/21outrigger.pdf

The calculated weight is about 1900g RTR (with fuel).

I plan to run without rear sponsons if it will be possible - my electric riggers run just fine without them.

Any tips/things to change, before I start building it ?

What kind of paint do you use ? (thinned (acethone) epoxy with color filler ?)

 

[Chris Wood]

I would HIGHLY reccommend rear sponsons..

paint i would look at

www.klasskote.com

great paint similar to k&b or hobbypoxy and shoots nice

as far as the weight.. no sure on grams but mine weight 3 1/2 lbs minus fuel.

chris

 

[Richard Dahlheimer]

I would HIGHLY reccommend rear sponsons..
paint i would look at

www.klasskote.com

great paint similar to k&b or hobbypoxy and shoots nice

as far as the weight.. no sure on grams but mine weight 3 1/2 lbs minus fuel.

chris

If your new boat is a manufactured kit, i would follow the instructions, provided. You will want to waterproof or seal the wood, before you begin painting. I like to apply a coat of two part epoxy, and sand it, before you apply the second coat. Just like Chris said, i would run the rear sponsons. If you have any more questions, feel free to ask. Many good boaters on this site. Richard D

 

[MitjaJ]

Here are some pictures of my rigger:

Tips and comments are welcome.

 

[Chris Wood]

couple of things..

this is just me own opinon.

the boat looks like it is going to be VERY heavy.. you have made the boat from all plywood correct... looks like 1/4??? next time look at making the boat with 1/8 balsa and sheet both sides with 1/32 plywood.. will save you a ton of weight.. same for the bulkheads ( minus the transom )

also.. where the drive line comes through.. not a good idea to have a bulkhead right on top of it.. you need to have room to put fiberglass or carbon fiber over the tubing area in the radio box.

how long is the boat because it looks REALLY LONG.

other than that looks like you have a good start.

chris

 

[MitjaJ]

The boat is made from 0.196 light plywood. The hull as it is now weights 9.8 oz.

It should be about 11-12 oz. finished. I first thought of using balsa ply sandwitch - but I saw (in the gallery)

riggers made from ply - so I decided to make it from ply.

The RTR weight of the finished boat (with fuel) should be around 4.2 lb.

The hull is 29.5" long. The prop is about 2" behind the transom.

 

[BB Mods's]

Whos motor are you running? and where did you find that collet??

 

[MitjaJ]

Whos motor are you running? and where did you find that collet??

The engine is made by Force Models LTD. (it is a car engine with water cooling)

The collet is from http://www.hydromarine.de/

 

[MitjaJ]

Glued the stuffing tube. The bulked is there to provide support.

 

[Chris Wood]

sounds good mitjaj..

from the pics it looked ALOT longer than you stated.. stuffing tube should be ok then. let me know how it works.

i would reccomend rear sponson.

chris

 

[MitjaJ]

I have som more questions:

How to finish/seal the hull with epoxy ? I'm afraid that the cure time of epoxy is quite long - so the epoxy will

start to collect at the edges (drips) - and I'll end up with an uneven surface. It happened to me once

I was finishing a electric hull - I never used this method again. But I have to make this hull fuel proof - anyone

tried 2 part acrylic lacquer ?

Is the cowl necesary (to prevent water getting in the carb) ? I have a 90 degree rubber tube form a RC car air filter

that I would like to use instead (so that the air intake points to the rear).

 

[Tom Foley]

Move the radio gear inside its own compartment for reliability , switch to one of the ultralite and small 21 rudders available out there . Just a few suggestions , looks good !

 

[Chris Wood]

yes.. epoxy is fine..

the way i seal a boat is this.

i use west systems epoxy.. brush a coat on let it sit for 10 mins or so. .wipe it off with a paper towl or cloth rag.. let it dry over night..

sand with a scotch brite pad or 400-600 paper.. then either coat again or use a epoxy based paint like i suggested earlier for your final coat.

and as far as the cowl YES it is VERY important.. not only for the motor to cover from water but it also effect's downforce on the boat.

chris

 

[shawdaddy]

I also use West systems but I put it on using a lint free paper towel. What little bit of lint that does tranfer will be sanded off between coats. Also I would change the rudder bracket, and the servo mount. On the rudder find a small piece of flat carbon fiber and there are a ton of people that make servo mounts that mound to the floor of the radio box. You can find them in carbon or alum. On the radio box the fewer hole you have in it the fewer chances for a leak. Just my 2 cents. Ryon Shaw

 

[Saugling]

Nice boat, just one question...why did you put the rudder on the left hand side? :huh:

We also started building riggers some years ago using "light" 5-6mm plywood...but quickly switched to ply-balsa-ply sandwich-wood or really light 3mm plywood for small (up to .21) boats.

What we learned...just seal the wood an do not paint the hull of a prototype. This safes you a lot of time & money and you will be more willing to make changes / modify the hull if things initially do not work as you planed

Have fun,

Robert

 

[MitjaJ]

...why did you put the rudder on the left hand side?

No special reason.

How strong is the ply-balsa-ply sandwich ? (especially where you drill holles to mount different things)

 

[Saugling]

Our ply-balsa-ply sandwich is normally 1mm - 4.0mm - 1mm (for boats up to .21). We also used 1mm - 5.0mm - 1mm or 0.8mm - 5.0mm - 0,8mm. Sometimes it just depended on ehat we had laying around. Anyhow, compared to solid 5 or 6mm plywood you save a lot of weight.

But run your boat as it is build now an see how it performes. You can always build a evolutionary step based on your first boat in the future.

To mount things to the tub I like these drive-in-nuts (german: "Einschlagmutter"):

http://www.modellbau-bichler.com/images/10...schl_mutter.jpg

Compared to a normal nut, you use more area to spread force.

 

[MitjaJ]

One other question. For sponson boom tubes I was planning to use 10 mm OD (0.393") carbon

fibre tubes - will I weaken them too much if I drill two holes (3 mm (1/8") dia) in the middle where

they mount to the hull ?

Like this:

https://www.intlwaters.com/gallery/albums/userp...5137-Keps06.jpg

Is it better to use larger tubes (12 mm OD) ?

 

[MitjaJ]

A little update:

 

[Saugling]

You can drill holes in good quality carbon fibre tubes, never experiences a problem. Just don't tighten the screws toooooooo much.

I personally would remove this rubber-tube on the carb. I don't see a need for it (maybe unless you are running with several other boats).

Pipe seems quite long too me...