Lewmar 140 - Fitting the Thruster Box; Installing the Box (Standard and Flange Base)

Lewmar Swing Thruster Product and Installation Manual ref 500146 iss.3 | 5
Cut the marked up hole in the hull with a jigsaw. We recommend you cut with an angle of 40 degrees to the hull
(see picture below).
A
140 Thruster A=160-170 mm
185 Thruster A=200-210 mm
250 Thruster A=300 mm
Locate the box with the inside of the a-edge a maximum of the width of the flange (10 mm) a of the hole.
Measure out dimension A and calculate the difference between the measured dimension A and the value for A
given in the table. Transfer this measurement to the fore-and-a side of the box using a marking gauge. Cut the
box to this line. The thwartships sides (fore and a) are fitted to the shape of the inside of the hull. Put the box in
place and check that dimension A has been accurately marked.
3.3 Fitting the box
Orientate the box such that the hatch will open up towards the normal water flow
direction.
3.4a Installing the box (standard)
⚠ ATTENTION!
Sand the outside of the box for a height of about 10 cm all-round to ensure good adhesion to the GRP.
Locate the internal rear edge of the box a maximum of the width of the flange (10 mm) a of the opening. Adjust
the lateral position of the box until the thruster tunnel goes down through the hole and the clearance on each
side of the tunnel is the same, so that it is centred athwartships. Then attach the box using a little rapid-curing
filler.
Check carefully that the sides of the box are not concave. If they have become concave, the sides of the box
must be pushed out with a strut while the box is being glassed-in.
Then check that the tunnel can move freely, and that, when it is deployed, the thruster wash will miss the hull.
NB! Do not apply the final laminations until the hatch has been fitted. Check carefully that the hatch clears the
hull.
Centre line
Hull
Hull
Box
40°