Cardinal Trailer Specs for Bertram 31 Hull

These dimensions were taken from "Buddy Boy", a 1973 FBC. There will be some minor differences between year models and from boat to boat, but if the proper adjustment allowances are designed into the trailer, there should be no significant problems.

Click for larger size images:

The Factory Cradle Diagram for the B31, (PDF format 114K)

The trailer for Gerry Santiago's B31 complete:

Posted By: brianb

Date: Wednesday, 17 November 2004, at 11:07 a.m.

In Response To: Cardinal Dimensions for Trailer (Capt Patrick McCrary)

Very nicely done. I am adding this to my little binder of reference information.

I have been down the road of a couple of trailer purchases, the first being a gooseneck professional hauling trailer that was modified to hold a 31. It is the easiest to manually load and unload a 31. It uses screw pads in a bunch of different places to hold the boat upright, but the boat mainly rests on its keel, which is 100% supported. I have found this trailer to be huge overkill on all but the roughest roads in the US or foreign roads. It can be overloaded, is rated for 22,000lbs, and has moved 29,000, and can lose 4 tires and still support a 31 with little problem on the remaining axle and tires in the overload setting. This trailer has been used for thousands and thousands of miles by myself and others. I use this one less and less due to size, weight, etc. It takes a lot more truck due to its size and weight in addition to the boats.

My next trailer was a 18,000lb aluminum trailer that had a keel support added along the back 20' of boat, and the regular 4" wide bunks modified to support and hold the boat upright on the trailer(moved outboard as much as possible), along with a set of double supports in the front of trailer. The key to using this trailer effectively is to tightly strap down the bow to the winch section to avoid flexing of the trailer, and resulting movement. I have trailered a 31 several thousand miles cumulatively on this trailer with no problems, and a cost of about 5,500 wholesale new from Florida. I use this one more often lately, especially if I do not have to manually load and unload the boat. I also use this one currently at ramps to splash and haul out my boats with few problems.

I have also on occassion moved a EMPTY hull on a aluminum 12,000lb stock aluminum boat trailer with great success. I would not recommend this trailer to use on a loaded boat.

Some key things to I have found are to properly support the keel, use tires that are overrated for the load, and do strap the boat down to the trailer, it will move. It would be very nice to have one of Pat's designed tow bits on the bow to effectively hold the bow tightly. Also have enough truck to STOP the load, any small truck can move a load, but if you cannot stop it safely you are screwed.



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