Model Boat Mayhem

The Shipyard ( Dry Dock ): Builds & Questions => Steam => Topic started by: KBIO on March 09, 2011, 04:28:18 pm

Title: Formula for cc versus size of the boat.
Post by: KBIO on March 09, 2011, 04:28:18 pm

Hello!
I have been through the forum trying to find anything about the way to calculate the cc's needed versus the boat's size.
There is a lot to see, but I didn't find anything concerning this point.
If I remember, I used  : cc = Length x width x heigth (@water line) x 2/3 for a tug.
I guess that there is better formula , and I would appreciate your help on this matter.
Thank a lot !
Cheers.

Title: Re: Formula for cc versus size of the boat.
Post by: gondolier88 on March 09, 2011, 10:04:34 pm

Hi KBIO,

Are you talking about the size of the engine or the volume of the hull?

Greg

Title: Re: Formula for cc versus size of the boat.
Post by: KBIO on March 10, 2011, 07:15:49 am

Hello Gondolier!
I am taking of the size of the engine.
Question: what size of steam engine(cc)  is requested for a launch (or a Tug) of 4 ft long.
i guesss that the power of the engine changes according to the weight and shape of the hull!
Thank you & cheers! :-)

Title: Re: Formula for cc versus size of the boat.
Post by: derekwarner on March 10, 2011, 07:57:18 am

KIBO....I am sure you would be familiar with the references provided on the JMC web site  O0 ...........Derek

Les conseils techniques de JMC

 cylindrée moteur
 poids du bateau
 
1 centimètre cube
 jusqu'à 4 Kg
 
2 CC.
 de 5 Kg à 6 Kg
 
3 CC.
 de 6 Kg  à 7 Kg
 
5 CC.
 jusqu'à 15 Kg
 
8,5 CC.
 de 14 Kg à 20 Kg
 
10 CC.
 de 16 Kg à 20 Kg
 
15 CC.
 de 18 Kg à 24 Kg
 
3 cylindres 7,5 CC.
 bateau de 1m40
 
3 cyl. 4,5 CC.
 de 6 Kg à 8 Kg
 
3 cyl. 1,5 CC
 de 3 à 4 Kg
 
 

Title: Re: Formula for cc versus size of the boat.
Post by: DickyD on March 10, 2011, 08:05:26 am

Or in English.

KIBO....I am sure you would be familiar with the references provided on the JMC web site  OK ...........Derek

Technical advice to JMC

 cylinder engine
 Boat weight
 
1 cc
 Up to 4 Kg
 
2 CC.
 the 5 Kg to 6 kg
 
3 CC.
 the 6 kg to 7 Kg
 
5 CC.
 up to 15 Kg
 
8,5 CC.
 the 14 kg up to 20 kg
 
10 CC.
 the 16 kg up to 20 kg
 
15 CC.
 the 18 kg up to 24 kg
 
3 cylinders 7.5 CC.
 boat 1m40
 
3 cyl. 4,5 CC.
 the 6 to 8 Kg Kg
 
3 cyl. 1,5 CC
 the 3 to 4 Kg
 

Title: Re: Formula for cc versus size of the boat.
Post by: KBIO on March 10, 2011, 08:19:08 pm

Good evening!
Yes I know, those figures that  JMC (and some others) are using.
I just wanted to know if , you guys around the world have another way to find out.
I found some litérature describing another way to calculate engine size versus Boat's weight.
I need to translate in English and I shall submit it for you to tell me what you think.
Thanks a lot anyway . I'll be back soon! ok2
Cheers!

Title: Re: Formula for cc versus size of the boat.
Post by: KBIO on March 11, 2011, 07:40:31 am

Hello!     
I found this formula on an old Steam Model Book, and I wonder if it is right or a bit pessimistic as some  4 ft models are moved w/ 3cc. (in a quiet pond, no wind).

Formula is :    Length x Width x Heigth
                                    a

Length is over all length
Width is over all width
Height is from the water line daown to queal.
a is a coefficient which varies depending of the country.

England    a    = 3000 pour L    =   75 cm            Holland      a    = 4350 pour L=      75 cm       
                    = 2800                =   90                                         = 4000            =      90
                    = 2700                = 100                                         = 3900            =    100
                    = 2500                = 120                                         = 3600            =    120
                    = 2300                = 140                                         = 3300            =    140
                    = 2100                = 150                                         = 3000            =    150

 

In France, we use the Dutch formula and we add 20%.
Ex , for a French hull:  L= 100 cm  B= 20 cm P = 10 cm ===>

                                                       100 x 20 x 10  = 5.1 cc + 20% = 6.1 cc
                                                               3900

The difference of these coeficients is explaned by the shape of the hulls. Dutch hull would be a bit wider than British ones.
Conclusion : I would apply Dutch formula for a Tug , British one for a launch, and French one for a classic
What do you think??
Thanks for your helpl! ok2