Where can I purchase #10 x 4.5" S.S. flat head machine screws for my handrails.

some of the very large Ace Hardware stores stock them, but perhaps in 5 or 6 in. and you may have to cut them down. Put a couple of nuts on, cut, and take the nuts off to clean the cut. I forget ... is that the original size? I replaced with one size larger figuring if they broke once ... they were underspec'd.

McMaster-Carr

threaded rod works really well that way you can cut to lenght I agree that the size is a bit small 1/4-20 threaded rod addresses the problem

roger, roger go 1/4 ... but wait I replaced the top handrails with SS and they were 1/4 studs. but then to put the handholds back on the inside I used 1/4. I didn't think the top wooden handrails where great to be stepped on a lot. but if you have a 200lber hanging on the handrail below ... that too is a lot of strain.

the screws broke on both boats ... I think what happens is we decide to reef in a bit of boat motion and the big heavy guys go up on deck to help out using the rails for foot support and when you have a 200+lb-er dead on the hand [foot] rail ... with just a tiny bit of erosion they break. or in any case they break the seal and allow water to get into the deck.

somewhere there is another thread on this.

Thanks for the help. The only place that I could find that carried that specific type was fastenal.