In the instant case, it was actually not petitioners duty to prepare the victualling statement. The allegation that this was part of his duty as chief cook and the fact that he was aware of such duty when he was interviewed for the post is only self-serving and without basis. The employment contract does not mention anything that this was part of his duty as chief cook.viii[8] A perusal of the victualling cost statement form meanwhile reveals that only the signatures of a Relieving Chief Steward and the Chief Master were required.ix[9] Nowhere does it contain that the signature of the chief cook was necessary. Even assuming that petitioner refused to obey the order of his superior to prepare a corrected victualling cost statement for December, although he maintained that he just asked for time to do it, as he was then busy performing his usual duty, which we believe to be the case, his refusal cannot be considered as one being characterized by a wrongful and perverse attitude. From the beginning, petitioner already intimated that he did not know how to accomplish the victual cost statement since it entailed some mathematical skills which he admittedly did not have. Indeed, to use his own words, he came aboard only to cook. His capability on manual skill was limited to cooking and nothing more and for which reason he applied for the job as chief cook and was eventually hired as such. The fact that he was able to do the victualling cost statements for the past three months was an extra work on his part. His failure or alleged refusal to go on with the work did not merit the severest penalty of dismissal from the service and his immediate repatriation without even affording him due process of law.x[10] Petitioners dismissal without a valid cause constitute a breach of contract. Consequently, he should only be paid the unexpired portion of his employment contract. However, the payment of the overtime pay should be disallowed in the light of our ruling in the case of Cagampan v. NLRC,xi[11] where we held that: Petitioners have conveniently adopted the view that the guaranteed or fixed overtime pay of 30% of the basic salary per month embodied in their employment contract should be awarded to them as part of a package benefit. They have theorized that even without sufficient evidence of actual rendition of overtime work, they would automatically be entitled to overtime pay. Their thinking is erroneous for being illogical and unrealistic. Their thinking even runs counter to the intention behind the provision. The contract provision means that the fixed overtime pay of 30% would be the basis for computing the overtime pay if and when overtime work would be rendered. Simply, stated, the rendition of overtime work and the submission of sufficient proof that said was actually performed are conditions to be satisfied before a seaman could be entitled to overtime pay which should be computed on the basis of 30% of the basic monthly salary. In short , the contract provision guarantees the right to overtime pay but the entitlement to such benefit must first be established. Realistically speaking, a seaman, by the very nature of his job, stays on board a ship or of vessel beyond the regular eight-hour work schedule. For the employer to give him overtime pay for the extra hours when he might be sleeping or attending to his personal chores or even just lulling away his time would be extremely unfair and unreasonable. We already resolved the question of overtime pay of worker aboard a vessel in the case of National Shipyards and Steel Corporation v. CIR (3 SCRA 890). We ruled: We can not agree with the Court below that respondent Malondras should be paid overtime compensation for every hour in excess of the regular working hours that he was on board his