> This was caused by the air in the rear chamber contracting. Remember,
> the outside air temperature was over 100 degrees and the air inside
> the chamber was at least 20 degrees warmer than that (I suspect it
> may have closer to 30 degrees warmer). After the hull was cooled by
> the cold water, and the temperature inside dropped considerably, the
> vacuum that was created was powerful enough to cause the deck to collapse
> slightly.

> The lesson learned from this event was --- "Don't forget
> to drill a relief hole in your bulkheads dummy!"

Well I guess this answers my question about the necessity of breather holes!

Thanks for sharing your experience with us!

Mike Spence