New member with a model of Lulonga. Looking for help.

[tiger.tim]

Hello everyone, I'm a new member living in the Midlands of Great Britain. I'm not new to boat modelling, in fact I've made several scale warships however I am new to paddlers. My problem is :- I've been given a beautifully made model of the "Lulonga" unfortunately it sails like an empty cardboard box. It has problems making headway or turning and if there is the slightest wind it gets blown all over the lake. The wheels are driven independently by two motors and chain drive, on turning one wheel goes forwards the other back this does not seem to make any difference on the water. The power source is a 12 v lead/acid battery. I am tempted to have the boat driven by prop and rudder and make the wheels rotate freely. Would bilge keels make any difference. Any advice is gratefully accepted.
         Best wishes Tim

[Eddy Matthews]

Welcome to Paddleducks Tim....

The Lulonga is a model that usually sails very well. It has a fairly deep hull and sits low in the water, so it shouldn't be affected by winds too much. The twin motors should give it superb control, it should be able to turn in it's own length, or spin on the spot.

It sounds from your description that things aren't right with your model.... If you could get a photo of it sitting on the water, and measure the speed of the paddlewheel rotation both in and out of the water at maximum rpm, that should allow us to see where things are going wrong and offer suitable advice.

My guess would be that the model isn't sitting deep enough in the water, and the paddlewheels are running too slowly, but the photo and the paddle speed measurements would confirm that.

Regards
Eddy

[jelley_baby]

Hi Tim I too have a lulonga and at first it was much to low in the water mainly because of the weight of the motors at the rear, and a significant amount of lead at the front to keep it level. I have changed the motors now to a smaller size with turns the paddle at about 150 rev/min max. At that speed it actually travels to quick so I have to use the control carefully. are your paddles home made or are they the Graupner type that has a feathering action. by use of the independent throttles mine will turn in its own length. There are some pictures of mine somewhere on the site with its original set up, and of it on the water.

[tiger.tim]

Hi Eddy and Jelly baby,
   Many thanks for the prompt reply. I'll get my Lulonga back on my pond this weekend to take photos, measurement etc. The paddles are homemade so I suspect they are copies of the ones in the plan. The speed controller seems to be a homemade one too. When turning the arms on the turning servo operate micro switches which reverse the motors. Jelly you say that your paddles turn @ about 150 rpm. I think I'm safe in saying that mine don't work at that speed. I'll check this weekend. best wishes Tim

[jelley_baby]

Hi Tim, 150 rev/min is the maximium speed on 12volts, but I am using two electoeze speed contollers one for each motor so I am in fact able to run the paddles at any speed from 0 rev/min up to the maximum of 150 rev/min, which I very rarely have to use. Graham

[tiger.tim]

Sorry for taking so long to reply, I cannot use the club lake at the moment  so have had to wait to take the winter netting off the pond. Here is a photo of my Lulonga. I had to lie down on the lawn to take the photo and have just noticed how high it is at the bow and low at the stern. I wonder if this is the reason why it has poor performance and blows about? Normally I am standing on a bank about 6 feet above the lake surface so have never had this view before.

[jelley_baby]

She looks good on the water, What I have done is to use a 12volt gel cell fitted right at the front as far forward as I was able to fit it. I also changed the motors that were in it originally to smaller ones that saved a lot of rear weight.
Originally when ballasted mine set it self right on the lower deck line as the waterline and if any one went passed water would flow over the deck so with the reduction in weight the lower deck is now 1cm above the water, and I also fitted a 6mm square batton along the edge of the deck all of which gives me 16mm of safety. You might just be able to see the battons on the photos.
All the best Graham

[tiger.tim]

Thanks for the quick reply. The  12v Battery is as far forward as it will go without me taking all the inside structure apart which I am loathe to do. From the photo can you say whether the bow is too high or the stern too low? I can certainly add more weight to the nose but again without major rework, I cannot easily move weight fro the rear. What do you suggest?

[jelley_baby]

Hi Short of the major work at the front or moving the motors forward, I don't really know. You could just try some lead ballast infromt og the battery and move the battery back just a little. Sorry I have now real solution.
Graham

[derekwarner_decoy]

Hi PD's......just  ..... tt

The bow does appear to be out of the water..........so to counter this which would also raise the stern........in a flotation test...

1. add the temporary necessary mass [lead] to the vessels bow area to rotate the vessel's water line by lowering the bow & raising the stern
2. accurately weigh this temporary necessary mass [lead]........read point 7. now
3. remove the black steam winch on the foredeck
4. drill a hole down thru the deck levels to gain access to the hull
5. substitute the known weight [temporary necessary mass [lead]] with lead shot [sports stores sell this]
6. use a plastic funnel inserted into and down to the hull level & gently pour the lead shot into the hull...the funnel is to contain or minimise the <<< to >>> spread of distribution of the lead shot
7. use the same plastic funnel to pour the required amount of epoxy resin to just cover the lead shot ...... re-read point 2. most epoxy resins have a specific gravity equal to approx 2kg /litre

Good luck.....Derek
 

[tiger.tim]

Many thanks Derek. I hadn't noticed that the bow was so high before I lay down and took the photo. I'll try what you suggest. Best wishes Tim