Recently, low speed large diesel engines which are two stroke type used in ship have been increased bearing damage at aft side of main engine due to the effects of inadequate shafting alignment. A double bottom of engine room including a main engine is growing tendency so that the hull thickness which is optimized is getting thin that the hull deforms easily and a propulsion shaft can't follow in deformations of the hull and main engine the reason is that the propulsion shaft has a opposite tendency, so bearings which are located in main engine should be occur damages.
A shafting alignment calculation is the first step in a shafting alignment process. The one of important problems is how can be estimated exactly for bearing reaction forces in the static state. It has to estimate exactly for bearing reaction to ensure stability about results of the shafting alignment work.
Main engine bearings have margin of load so that they prevent before damage and it needs to design flexibly so that it copes with the several situations. It needs to calculate alignment which is including main engine bearings and to do alignment calculation of high accuracy including them when measures are considered .
Main bearings which are considered in alignment calculation including main engine bearings and shapes of engine internal modelling should be reviewed. On this review is investigated calculating method of exact bearing reaction, further.
There are not any regulations about number of main engine bearings to consider shafting alignment calculation. And commonly, shafting alignment considered by around four main engine bearings is calculated in tail of hull. Bearing reaction forces which is considered in variable shafting alignment is that depend on main engine bearing, so that it needs to review. On this wise, as stands on reviewed results it is investigated to search for bearing reaction forces exactly to number of main bearings in shafting alignment calculation.
The shafting alignment calculation dose not correspond with the real modeling of engine internal shapes. Most of the shafting alignment calculations assume that a crank shaft is continuous beams and it is calculated by offering data from engine maker.
On this wise, when shafting alignment is calculated bearings reaction forces which are depended on main engine bearing and engine modeling shapes are reviewed so that it is investigated to search for methods for exact bearing reaction forces. As the results of the methods, results which are about shafting alignment work ensure stability.