How to estimate a boat's weight ?

[Trevano]

I am new to boat building and am participating in the design of a revolutionary type of push boat. A possible design is to make the push boat in three separate parts : an accommodation unit and two propulsion units. A propulsion unit would be about 2.5mx5m in dimensions and would have no crew. For regulation purposes it could be useful of the propulsion units were unsinkable. To know how much buoyancy I need when the hold floods I would need to know the total weight of all the components. I think the information is useful anyway for any boat design so such information must exist. Where can I find help for estimating the weight of those components ?

A propulsion unit would probably contain (some terms may be bad translations from Dutch)
- Hull
- steering machine
- propeller-shaft installation
- nozzle + propeller
- engine 250-300 kW
- twin disc coupling
- motor cooling element (Dutch: beunkoeler)
- generating set 40kVA
- coupling winches
- electrical equipment

I suspect we would use an orientable propeller ISO a rudder and wont need any ballast tanks.

Cheers,
Trevano

[rwatson]

What the heck is a push boat ??? and why would you flood ballast tanks?

Are you talking about some sort of submarine?

[TeddyDiver]

Originally Posted by Trevano

Where can I find help for estimating the weight of those components ?

Internet? Seriously, you gotto do the design "spiral" Choose the equipments, add up weights, design the hull, calculate hydrostatics, change equipments, add up weights, redesign the hull, calculate hydrostatics, change equipments, add up weights, redesign the hull, calculate hydrostatics,change equipments, add up weights, redesign the hull, calculate hydrostatics.... until you done..

[clmanges]

Teddy's got it about right, I think . . . start with a best approximation and revise, revise, revise . . .

[netjaws]

cool idea though with the modules

[Trevano]

Originally Posted by rwatson

What the heck is a push boat ??? and why would you flood ballast tanks?
Are you talking about some sort of submarine?

A push boat is tugboat specifically for pushing barges.
We wouldn’t flood ballast tanks. We may not need any as the boat would probably be already heavy and we lack the space if we want to make it unsinkable.

Originally Posted by TeddyDiver

Internet? Seriously, you gotto do the design "spiral" Choose the equipments, add up weights, design the hull, calculate hydrostatics, change equipments, add up weights, redesign the hull, calculate hydrostatics, change equipments, add up weights, redesign the hull, calculate hydrostatics,change equipments, add up weights, redesign the hull, calculate hydrostatics.... until you done..

I have looked on the internet.
Before spending a lot of time on the design, it would be useful to know whether the design is at all feasonable by having a reasonable estimate of the weight. With a mundane boat you don’t run the risk of discovering after a while that your boat would sink under its own weight or lacks the space to house its equipment.

[TeddyDiver]

Originally Posted by Trevano

Before spending a lot of time on the design, it would be useful to know whether the design is at all feasonable by having a reasonable estimate of the weight. With a mundane boat you don’t run the risk of discovering after a while that your boat would sink under its own weight or lacks the space to house its equipment.

There's a wide variety of machinery you are planning. So the the weight varies accordingly. Best to contact resellers and ask them to send you some brochures and tech specs etc..
If you have a weight limit wonder how much?