Technical data

The alignment is correct when the shaft canbe slipped backward and forward into the

counterbore very easily and when a feeler gauge indicates that the flanges come exactly together at all

points. The two halves of the propeller coupling should be parallel within 0.002 inches (A).

In making the final check for alignment, the

engine half coupling should be held in one position and

the alignment with the propeller coupling tested with the

propeller coupling in each of four positions, rotated 90

between each position. This test will also check whether

the propeller half coupling is in exact alignment on its

shaft. Then, keeping the propeller coupling in one

position, the alignment should be checked rotating the

engine half coupling to full position each 90

from the next

one.

The engine alignment should be rechecked after

the boat has been in service for one to three weeks and, if

necessary, the alignment remade. It will usually be found

that the engine is no longer in alignment. This is not

because the work was improperly done at first but because the boat has taken some time to take its final.

shape, and the engine bed and engine stringers have probably absorbed some moisture. It may even be

necessary to re-align at a further period.

The coupling should always be opened up and the bolts removed whenever the boat is hauled out

or moved from the land to the water, and during storage in a cradle. The flexibility of the boat often puts

a very severe strain on the shaft or the coupling or both when it 'is being moved. In some cases the shaft

has actually -been .bent by these strains. This does not apply to small boats that are hauled out of the

water when not in use, unless they are dry for a considerable time.

EXHAUST SYSTEM

Exhaust line installations vary considerably and each must be designed for the particular job. The

general requirements are to provide an outlet line with a minimum of restrictions and arranged so that sea

water, rain water or condensation cannot get back into the engine. There should be a considerable fall in

the line between the exhaust manifold flange and the discharge end. This slope in the pipe makes it

difficult for water to be driven in very far by a wave, and a steep drop followed by a long slope is better

than a straight gradual slope. Avoid any depression or trough to the line which would fill with water and

obstruct the flow of exhaust gas. Also avoid any sharp bends.

Brass or copper is not acceptable for wet exhaust systems, as the combination of salt water and

diesel exhaust gas will cause rapid deterioration. Galvanized iron fittings and galvanized iron pipe are

recommended for the exhaust line. The exhaust line must be at least as large as the engine exhaust

manifold flange and be increased in size if there is an especially long run and/or many elbows. It should

be increased by 1/2" in I.D. for every 10 feet beyond the first 10 feet.

Most exhaust systems today use a water lift type muffler such as the Westerbeke "Hydro-Hush".

In most installations there is a dry, insulated high loop after the engine manifold and before the muffler to

prevent water flowing backwards into the engine during cranking