The jack uses multiple combinations of a 2-1/2" engine offset with or without a six-degree positive wedge; a 5" offset with or without a six-degree negative wedge; or both offsets using no wedge. The best combination of offset and wedge is manually adjusted to provide maximum speed, handling and performance.
For example, a boat with a steep transom angle of 18 degrees can be changed to a 12-degree angle by simply converting the jackplate to the 2-1/2" engine offset with the six-degree wedge. Jacking bolts are used to adjust the vertical height of the jackplate up to 4".
For most lightweight boats, using the 2-1/2" offset alone is normally enough to raise the engine to its highest level without creating excessive bow lift. For outboard motors with a limited trim angle and insufficient bow lift, a 5" offset with no wedge can be used.
Use of the 5" offset and the 6-degree wedge together positions the engine 5-1/2" behind the transom into clean water and away from bubbles and hull turbulence. This helps to stop prop slippage and improves steering.
The standard MJ5 model weighs 19 pounds and is designed for engines with less than 225 hp. The heavy-duty MJH model weighs 27 pounds and is available for off-shore use with engines up to 300 hp. All jackplates are pre-drilled with the standard, BIA bolt pattern and will fit late-model V-6 engines. The jacks can be easily modified to fit any size outboard.
These jacks are constructed of aircraft-grade aluminum and stainless steel, and anodized with a black finish for corrosion resistance. They come with Bob's Machine Shop's limited-lifetime warranty to the original owner.
Retail price of BMS's standard MJ5 model jackplate is $249.95. The heavy-duty MJH version sells for $269.95, and an 8" version is available for $299.95.