Engine Plant Mass

[navarch_hish]

I am designing a high speed displacement catamaran, i am in the intial stage of the design, i need to determine the intial weight of the engine plant..

Are there any formulas which give me approx formula for Engine plant mass with diesal engine (4 , 2 in each hull) 4 waterjets..

Can someone tell me what all components to consider in engine plant mass calculation?

Its a little bit urgent , so i would be greatful i could get a reply soon.

[Eric Sponberg]

No, there are no formulas to determine the engine plant mass. You will have to use a little brute force calculation and estimating to arrive at a reasonable answer. First you have to determine the approximate horsepower that the boat will need, and search out engines from various manufacturers--they all post their weights, sometimes with a reduction gear attached. If no reduction gear is included, you have to search out the reduction gear manufacturers and see what fits with the possible engines for the rated horsepower. Then you have to do the same background checking for the shafting and propellers. You'll likely need a diesel genset or two, so you go through the same process for those. The same applies for all the rest of the equipment on board. There are no easy ways out.

Over time, you will develop a knack for making preliminary weight estimates. Having gone through a few design scenarios, you will be able to determine the overall weights accumulating in any category--hull & deck structure, interior joinery, interior/exterior outfit, deck equipment, machinery, electrical, plumbing, consummables, liquids, etc., most of which vary with the cube of the length for the boat. That is, similar boats will generally have similar weight proportions in each category, and the amounts of those weights vary by the cube of the length (or by the product of LxBxD--length x Beam x Depth of the hull).

I recommend buying Cy Hamilin's book, "Preliminary Design of Boats and Ships" which is available at a discount at Amazon.com. This will give you some guidance.

Eric

[alex fletcher]

most manufactures will give designers the info u need. Decide on what engine brand u wont to use and contact them thay should send u a auto cad file for dimensions and a PDF file of states and specs to help you specify their equipment
after all as thay see it you are a sales tool. Alex