How was the vented transom done on these boat's? Sounds like a good idea .
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How was the vented transom done on these boat's? Sounds like a good idea .
Seem to remember a hollow transom with holes drilled at the top facing the inside of the boat and a bunch of corresponding holes drilled along the outside lower edge of the transom about an inch up from the bottom.
If as Ed says it is the case with holes in the transom the idea was to reduce the dead air behind the transom in an attempt to reduce drag. How was any improvement measured?
I recall a case when I was racing in 25ssh and a competitor Dave Rawson was experimenting with a similiar idea except he was picking up air just in front of the cowl at the deck line. He then ran air thru 2 tubes left and right inside the boat that exited at the rear in an attempt to reduce drag. Results were not conclusive. He dropped the air intake design on later hydros. Don't know if Dave saw the Craig idea and then developed his or vice versa.
I saw the vented transoms on Craig's boats during the summer that Craig and Lee Sutter spent in Wisconsin, mid 70's I think, building boats. John Puestow asked me to design and build a CSR for him so I decided to incorporate a vented transom in the design. I put several holes on the Inner transom face and glued up the spruce framing so it ducted to the outlet ducts in the aft transom face just above the bottom. These ducts were in the form of rectangular cut outs with routed edges to also serve as the lifting handles. We could not quantify any enhanced performance but noticed that the transom had a significant reduction in oily exhaust residue so the dead air swirling behind the transom must have ducted off into air stream coming over transom. It is a moot point as APBA stock rules outlawed them a few years later!! Jon K Walters