caulking on rub rail?

[Elie]

hey guys,
yet another question - I have caulking only on the back of the rub rail. Is it supposed to be calked/sealed all along the length of the boat? if so, what do you recommend using?
see attached pics to see what I mean...
Thanks for your help!

 

[Capt jgw]

I don't think out has to be sealed, but sealing it will help keep the boat cleaner. I've had gaps like that on mine, and when I washed the hull or after a heavy rain all manor of crud and corruption would come bubbling out of the gap. It took several passes with the hose to rinse it out . If it freezes where you are, that could cause the gaps to open up more.