The Isis Project
Its always been the aim of the club to provide a broad range of snorkeling and diving opportunities for the members. In 2010 to help with this goal we decided to purchase a second diving boat, to compliment the diving available from Gemini. We didn’t have a lot of money to spend so a new RIB as usually used by BSAC clubs was pretty much out of the question.
Our boat officer suggested a cheaper alternative might be a DORY style boat so we set off to look into these. In general these are popular amongst fishermen but divers seem to be wedded to RIBs. We tried to work out why this was the case when RIBs are typically more expensive than DORY style hulls. A lot of hot air was filtered to get down to the key factors that divers think make a RIB superior.
RIBs
- are unsinkable and hence more secure in rough seas
- are mores stable in a rough sea
- tubes are very robust and can survive lots of abuse like dive kit being dropped, dragged over or leaned on them.
We wondered about some of these
The DORY hull has a closed in honeycomb structure beneath the floor which makes it very hard to sink. You prcaticaly have to rip the bottom off to do this.
Most modern DORYs have a semi cathedral hull design (like the Solent Fisher or Wilson Flyer) which, whilst a little less stable for small roll angles is in fact just as stable as a RIB for larger roll angles (as defined by the restoring moment and the relative centre of buoyancy)
No tubes do mean you are prone to damage if people drop heavy / hard things like cylinders or weight belts on your gunnels. This is a definite plus to RIBs.