The Principal Act is hereby amended -

(a) in section 284, by the insertion of the following subsection after subsection (3):

"(3A)

(a) This subsection applies to machinery or plant consisting of a sea fishing boat registered in the Register of Fishing Boats and in respect of which capital expenditure is incurred in the period of 3 years commencing on the appointed day, being expenditure that is certified by Bord Iascaigh Mhara as capital expenditure incurred for the purposes of fleet renewal in the polyvalent and beam trawl segments of the fishing fleet.

(b) Notwithstanding subsection (2), but subject to subsection (4), wear and tear allowances to be made to any person in respect of machinery or plant to which this subsection applies shall be made during a writing-down period of 8 years beginning with the first chargeable period or its basis period at the end of which the machinery or plant belongs to that person and is in use for the purposes of that person's trade, and shall be of an amount equal to -

(i) as respects the first year of the writing-down period, 50 per cent of the actual cost of the machinery or plant, including in that actual cost any expenditure in the nature of capital expenditure on that machinery or plant by means of renewal, improvement or reinstatement,

(ii) as respects each of the next 6 years of the writing-down period, 15 per cent of the balance of that actual cost after the deduction of any allowance made by virtue of subparagraph (i), and