Engbo XForce Series - Grinding Tunnel Openings; High Speed Boat Tunnel Installation; Tunnel and Hull Coating

XF Rev: 7, 2008-10-14 Page 13
5.1.10 Grinding
Working from outside the hull the outermost edges of each hole should be
ground at an angle of 45 degrees to the innermost edge of the hole.
A: Grind the complete circle at 45 degrees.
To achieve maximum thrust and minimum noise, round off the openings
with a radius Rmin=d/10 (10% of the tunnel diameter).
5.1.11 Directions for high speed boat special installations
On fast boats it may be necessary to make structural alterations to divert
the flow of water in front of the tunnel. This is to prevent water slamming
into the propeller.
A: Level with the hull.
B: The tunnel should protrude 25 mm from the hull.
5.1.12 Coating
Prime the hull exterior with two coats of two-component primer. Apply
bottom coat to both the hull and the tunnel.
Apply topcoat
Grind all areas that have been moulded or ground and apply topcoat to
avoid water access to the hull / tunnel.