{"id":13195,"date":"2010-09-15T17:14:15","date_gmt":"2010-09-15T22:14:15","guid":{"rendered":"https:\/\/setsail.com\/?p=13195"},"modified":"2010-09-16T01:12:59","modified_gmt":"2010-09-16T06:12:59","slug":"naiad-stabilizer-fin-replacement-and-questions","status":"publish","type":"post","link":"https:\/\/setsail.com\/naiad-stabilizer-fin-replacement-and-questions\/","title":{"rendered":"NAIAD Stabilizer Fin Replacement and Questions"},"content":{"rendered":"

\"NAIAD-Fin-Replacement-103.jpg\"<\/p>\n

We’ve had a four hour hang in the slings in Palma to replace our damaged stabilizer fin. We are not happy with what we found.<\/p>\n

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\"NAIAD-Fin-Replacement-102.jpg\"<\/p>\n

The leading edge of the keel, which hit just before the port stabilizer. Note that the microballoon fairing on the keel is dinged, but the undercoat is still intact. This is a good indicator of the probable loads, which were light.<\/p>\n

Before we get \u00a0into what we think of the fin engineering, let us say that we have been very pleased with the NAIAD performance and service. There have been some hydraulic QC issues on all the boats so far, but the system, once operating, has been excellent. We have discussed the comments which follow with them and they have their reasons – right or wrong – for doing things a certain way. They are not going to change what they say works in fin construction for one small customer.<\/p>\n

Our logic in cruising yacht design is that mistakes happen. People run aground, hit logs, bang into ice. This is part of cruising. We want to be able to make modest mistakes – such as the one which caused this damage – without having to visit a boat yard. Hence our keels are designed to four times the ABS rule, rudders to twice.<\/p>\n

\"NAIAD-Fin-Replacement-100.jpg\"<\/p>\n

Two things immediately draw your attention to this stainless insert formerly molded into the fin. The first is the lack of foam adhesion to the stainless.<\/p>\n

\"NAIAD-Fin-Replacement-101.jpg\"<\/p>\n

The shearing on the foam surface on the other side is what we would expect everywhere<\/em>. The bond line between foam and its substrate, properly done, is normally the strongest point in the foam.<\/p>\n

\"NAIAD-Fin-Replacement-105.jpg\"<\/p>\n

The second item is the size of the stainless insert relative to the fin. This is maybe 1\/12th the fin’s area. Even if the foam had not released it would have quickly sheared off this small area.<\/p>\n

Now some logic. The way we want to engineer a risk element like a stabilizer is so that the damage occurs outside of the boat. Ideally:<\/p>\n