Deck Stepped Mast - Dish situation

[tcrespo]

Hi all - I've got a 1975 O'Day 20 that has had a soft spot around the mast step for some time. The top of the cabin is slightly dished, although the step itself seems pretty solidly connected. Inside, all of the bolts are nice and tight. There's no compression post on this model (at least, this boat never had one) and the inside roof of the cabin is not distorted in any way.I had planned on replacing the fittings for the shrouds and started that project this morning. Got it taken care of with no problem, however, while the shrouds were off on one side (and before I had properly secured the mast), it started to go over. The step started to come loose, although I was able to stop everything before I lost the mast. Anyway - my question - I replaced all of the fittings for the shrouds (re-bed them all, new hardware, etc) and that's all set (a fairly easy and quick repair). What about the mast step? Should I immediately pull the boat out of the water and attend to this, or am I okay for a bit? All of the shrouds are now nice and tight, and things look pretty solid. Is the mast step "critical" or is it really there as a base for the mast (what I mean by that is - the shrouds/stays are really what keeps the mast up - not the base, correct)?I really hate to pull the boat out of the water and start replacing the core material at this time. I'd rather do that when I pull her out for the winter. I'm really looking for opinions here - am I tempting fate, or should I be okay for a while? We sail mainly on inland lakes, and nothing real aggressive.Thanks - Tom

 

[Brian M H23]

Physics

All the stays pull *down* on the mast, as much if not more than they pull to the sides. so, if you have 5 stays, each tensioned to 500 lb and at 30 degrees, plus 150 lb of mast. At 30 degrees, the tension is 85% downward acting, and 50% sideward acting. Each shroud is pushing down by about 420 lb, or a total downward force on the mast step of abut 2200 lb. And 30 degrees is a very wide angle..I think the side stays on my H23 are more like 15. That being said, it's pretty common for this stuff to deform under constant loading, especially with no compression post. Assuming there's no cracking, I wouldn't worry about the thing crashing through the cabin roof anytime soon. I'd personally sail the boat if everything looks tight, the rig is tight, and this dishing isnt too severe / the core itself isn't *rotten*. If the core is soggy and rotten, I'd be a little more worried. My personal feeling is that the fiberglass itself has taken this dish shape over time (30 yr old boat) and the core probably isnt suspect, the only way to fix it would be to add in a compression post and shim the cabintop back where it should be.

 

[tcrespo]

Great input...

Thanks for that explanation - funny how when things happen, you don't stop and think it through, but instead panic (a bit) and think the worst. After reading what you wrote - makes perfect sense. 30 year old boat is going to have a settling around the mast. Shrouds and Stays put a lot of downward pressure there.Thanks again - I feel better already and I'm confident that I'm good to go!Tom