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[jim c]

hi guys i need some helpful advice,have started to build dumas kit creole queen ,a mississippi stern wheeler,have glassed the wooden hull now it is too heavy with a sealed lead battery on board the lower deck is awash even in the bath,what can i add to the keel to aid buoyancy  any helpful replies will be welcome.jim c.

[cos918]

have you thought about a LIPO battery about 70 to 80% lighter than SLA


john

[jarvo]

Adding blue foam to the bottom of the hull would raise the waterline by the thickness of the foam


Mark

[Colin Bishop]

The danger with adding buoyancy to the bottom of the hull is that it can compromise stability. A lighter battery will certainly help but if you have been testing the model without the superstructure built/fitted and it is still too low in the water then I'm afraid it may be a lost cause as a working model. You also need to weigh the parts that have still to be fitted to the hull to confirm its carrying capacity. From reports on the web, some people have added an inch or so to the hull depth to improve buoyancy and stability.

If you decide to add foam to the bottom of the hull then cut out a central section and plate it over underneath so the battery can sit lower in the hull within the thickness of the foam.


As a first step I would suggest that you float the empty hull and add weight to bring it down to the correct waterline. This will give you your max payload. Then weigh all the superstructure and other bits that need to go on the model including the motor. The difference is what you have available for battery and radio etc. This will give you an indication of how bad the problem is.

Colin

[derekwarner]

jim c.....welcome to MBM as a builder  ....all is not lost by any means

River paddlers of this type by original design and build had very little freeboard

Follow the last paragraph by Colin ......accurately & carefully...you may need to invest in an el-chepo set of digital scales....

"As a first step I would suggest that you float the empty hull and add weight to bring it down to the correct waterline. This will give you your max payload. Then weigh all the superstructure and other bits that need to go on the model including the motor. The difference is what you have available for battery and radio etc. This will give you an indication of how bad the problem is"

eg.,......6.?? kg is not near enough by eye on one of those old kitchen or bathroom scales.......use all of the second decimal point....that weight was actually 6.277 kg............these amounts will add up surprisingly quickly


The beauty of this approach will also confirm [not guess] the allowable weight of assemblies other than the hull, but also confirm any increased depth of hull required

Here is my example.......I guessed about 6 kg  from the bathroom scales .....the cheap digital proved me wrong by 277 gms.......the weight of every component is very important here

Good luck......let us know how you get on

Derek

[JerryTodd]

How is your hull built?  If it's been glassed, odds are you can lose a great deal if not all of the framing inside.

[canabus]

Hi Jim

As the drive kit uses 12 volts, these are some Lipo battery weights which may help you out.

These are all 3S (11.1 volts fully charged they go up to 12.6 volts).

These are from the Hobbyking website:- Turnigy 1000mah(75x33x19mm) 89 grams (these are the real weights which I have measured).
                                                           Turnigy 1500mah(80x34x25) 113 grams.
                                                           Turnigy 2650mah(137x44x18) 250 grams.
                                                           Zippy Compact 3300mah(139x45x240 288 grams.

[Tug-Kenny RIP]

When I scratch built mine I made the hull a little deeper from the deck downwards.  This was because I knew there would be extra weight above with a  heavy battery and all the extras.

May I suggest that you remove the deck and built another layer up the hull sides to raise the height when you refit the deck.  No one is going to see this alteration when she's afloat.

Have you any pictures ?

Cheers ken



 

[jim c]

hi thanks for your advice but have built 2 cabin decks, so to raise hull is i am afraid a no goer ,will consider lipo batts ,i rather like the idea of foam on underside will give it a try ,many thanks for your efforts .jim c.