2005 - BLUE MAX Refit - Bulbous Bow & Aft Extension

Wayne sometimes suffered from sea sickness especially when the boat pitched. It was in 2000 when he first wondered if by adding a bulbous bow & extending the water line length might reduce the problem. Several years of research proved that it was possible, so in 2005 (ten years after he purchased BLUE MAX), while the boat was on the hard in Key West for thru-hull replacement and bottom paint, he decided to make the modifications he learned & hoped would eliminate the pitching.  He began the difficult task of designing  then incorporating his ideas into BLUE MAX; she was in the yard for 13 months.(January, 2005 to February, 2006)

Shows the conceptual mock-up used to determine proportions & position

This is the structural 'spine' of the bulbous bow

Problem: how to make a sphere for the tip of the bulb. Solution: A large round fender was used as a plug

Half of the plug was fiber-glassed over

I intended to use this as a mold but instead, used it as is (see next picture)
 

Shows the tip of the bow in position (refer to the previous picture) Also shows the spines attached & the ribs to support the sono-tube (foreground) & the extension of the bow thruster tunnel. 

The cardboard tube was cut into four quadrants & fastened to the ribs then it was filled with closed cell foam & the the cardboard was removed.

 

The lay-up schedule consisted of 12 alternating layers of 24oz Fabmat & 17oz Biaxial cloth. Each layer overlapped each other layer on the spherical end so the thickness at the center of the bulb was 24 layers at over 1.3"  thick to provide impact resistance. A final layer of Kevlar cloth was then covered with Biaxial cloth. Epoxy resin was used throughout. After fairing, to make it smooth, 3 coats of epoxy, mixed with barrier additive was applied. 

The keel was blended into the bulb so as to prevent pounding when the bow slams down into a wave.

 

This shows the sand shoe on the keel made of 20' long, 316 SS fabricated channel & also shows the enlarged rudder which makes the boat steer more efficiently.

Finished product before launch.

 Yippee! - It floats

After all his research, Wayne's theory is this:  "Under sea-conditions that might be rough or choppy, the bow of a boat dips down with the waves then quickly pops up which creates the pitching effect. Adding a bulb modifies  the way the buoyancy changes as the bow plunges and rises thus reducing the depth to which the bow dips or how high it rises as compared to a more normal bow shape. You will still have some pitch but it is far less extreme".

 AFT EXTENSION

Establishing the shape of the extension (note, the old swim platform still in place)

Preparing to lay-up fiberglass (note, the old swim platform is now being used as a scaffold)

This photo shows the discarded form that was used as the mold for the extension. It also shows the original, smaller rudder

 

The extension has 3 separate compartments filled with batteries to compensate for the additional buoyancy - This picture shows the extension of the exhaust pipe before any batteries were installed.

The swim deck is 1" honeycombed core. Epoxy glue was used to fasten it to the extension

Finished product with new, teak swim platform resulting in a very large swim deck.

Forming the buttress

The buttress is not structural but for appearance only.

Wayne made a fixture and used a special tool to extend the plank lines into the buttress.

32" hull extension completed & shows the new swim platform with boarding ladder.

 We've lived with these changes & cruised extensively for 9 years & the changes made resulted in a significant reduction in pitching. Many have asked us if the bulb has improved our fuel consumption or cruising speed. But with having only 139 hp. & consuming only 2.5/3.0 gph. we don't see a difference. We cruise at 1800 RPM which is about 7 knots -- top speed is 8.3 knots.

In addition, the swim deck has many uses & is a great spot for lounging at anchor.