Using a bungee on the daggerboard instead of its angled bolts and wing-nuts

— July, 2006 —

I am willing to bet that practically anyone who contemplates for the first time the bolts and wing nuts that hold down the daggerboard on a P-19 would react with bewilderment and even a bit of fright. The way those bolts stick out at an angle, right at shin’s height, strikes one as a painful boo-boo just waiting to happen.
However, there is a method to International Marine’s madness. Those bolts are purposely mounted at an angle so that, if the daggerboard ever bottoms out, the impact will not only be directed up and back, but also diagonally, popping out the hardware’s tiny screws. Otherwise, such a collision could do serious damage to the daggerboard’s trunk. If and when such a mishap occurs, you are supposed to re-epoxy the stripped screw holes and re-mount the hardware.
Well... I got to put that safety feature to the test this year. I sailed into an area shallower than I thought and —whump!— the daggerboard struck bottom. When I went below to see if there had been any damage, I found that, sure enough, the screws on the daggerboard’s rear bolts had indeed popped out. I was at least glad to see that the system really worked and that the trunk was still intact.
Maybe I am too lazy, but having to re-epoxy and re-mount that hardware before I could again launch Harried Potter did not appeal to me. Moreover, I will admit that I have no expertise when it comes to working with fiberglass and was fearful I would only screw the job up (pun intended). I decided to see if I couldn’t come up with a better way of securing the daggerboard when it was down.
The upper rear hardware had already fallen off the daggerboard, so I decided to remove the front pieces as well. This left the bottom pieces with the little double hooks on the trunk itself.

As I contemplated those hooks, it dawned on me that perhaps I could use them to string an industrial-strength bungee cord over the daggerboard. I had such a bungee on hand, 3/8" thick and 3 feet long, just enough when stretched to wind it around those hooks in the pattern illustrated to the right, steps 1 to 4, as seen from above looking down:

Suggested pattern to stretch a bungee among the hooks

Since the bungee criss-crosses over the daggerboard four times, I figure I am nearly quadrupling its holding strength. It goes straight over both ends (probably where the security most matters) and crosses in the middle (still allowing me to use my releasable double-pulley). Most important of all, I assume that the bungee will likely “give” somewhat if and when I ever strike bottom again, thus protecting the trunk from structural damage.

Bungee cord on the daggerboard
To the left is a photo in which you can see my bungee on the daggerboard cap. I have been using it ever since and haven’t witnessed any serious problems.
However, I would be less that truthful if I didn’t mention that, one afternoon, when we were plowing upwind through waves bigger than our boat, my admiral noticed that the front end of the daggerboard would sometimes “burp” a bit of water out through its gasket. Nonetheless, it was not enough to pool on the floor, just spit a few drops onto the compression post. From what I have read in the Potter forum, I understand that even the original bolts and wingnuts allow that amount of leaking in similar conditions. And the good news is that our shins remain unscarred.
I must confess, however, that I have not yet run across an opportunity to truly put my bungee solution to the test. I haven’t bottomed out again, nor have I turtled the boat to see if the elastic is strong enough to keep the daggerboard from falling down (up) to the cabin ceiling. If another P-19 owner would like to volunteer to perform such an experiment... I would be more than happy to supply the bungee!

— May, 2007 —

I got to put my bungee solution to the test while at Lake Powell. We sailed to the far end of Bullfrog Basin, turned around, and were heading back when we heard a muffled thump, and the boat started to slow down. I immediately looked at the daggerboard, and —sure enough— it was pushing out of the trunk, with the bungee stretching up about 8 inches on the back and 4 on the front. Obviously, we had struck bottom and the bungee effectively “dampened” the impact, bringing us to a stop. This happened two more times before we got back to deeper water, once at nearly full speed with the motor. In all instances, the bungee performed flawlessly. I am now much more confident about the bungee in lieu of the original t-bolts and wingnuts.
As to whether the bungee would retain the daggerboard if turtled, I confess that I haven’t tested out that scenario —and never hope to. Nonetheless, I have looked up the tensile strength of bungees on the web. What I found was that a 3/8" bungee has a tensile strength of 375 lbs. One site even claimed 400 lbs. —but it's probably safer to stick with the lower number.
Since the bungee criss-crosses the daggerboard four times, that would suggest a theoretical breaking limit of: 4 x 375 = 1,500 lbs.
On the other hand, we know that knots reduce the tensile strength of line, so I assume that winding the bungee around the trunk's lower hooks might do the same. For argument’s sake, let's assume that it even reduces the breaking limit by as much as half: 1,500 x 50% = 750 lbs.
Well... that is still more than twice the weight of the 300 lb. daggerboard. I therefore have a hard time imagining that it could fall down (up) to the ceiling if my boat turned turtle, so I am no longer worried about that ever happening.