I bought a bimini from Overton''s for my Helms 25 which I''m going to assume is similar to your ODay 25. I''ll assume your cockpit is about as roomy as mine. If this is so, a bimini should work for you.
Figure out where you want to mount it. Primary issue is where your main is sheeted; boom end (like my boat)? Front of the cockpit? Cabin top? Either of these are OK but will determine where you can fit the Bimini. A mid cockpit mainsheet and traveler location would probably necessitate redoing the mainsheet setup if you want to be able to sail with the bimini up (and why wouldn''t you?)
Measure the headroom you have under the boom when the sail is hoisted. Can you stand in the cockpit with your head under the boom when it is sheeted in tight and not have to crouch? How much room do you have to spare? Enough to fit an inch or two of tubing and cloth?
Here''s a photo from the ODay website showing a bimini.
Looks like this owner has a mainsheet leading to the middle of the cockpit floor; God knows how he manages to sail with the bimini up. Maybe he just doesn''t do close hauled.
His location looks about where mine will end up in terms of mounting. Think about where your jib sheet and other control lines go relative to the cockpit coaming and winches and so forth. Do you want to stow the bimini back like in the photo when you''re not using it? I bought some quick release mounting brackets so I can remove it quickly and stow it below on race night.
The three main measurements you need before you''re ready to order are length, height, and width, obviously. Figure on the mounting brackets going roughly in the middle of your length dimension. I measured forward 6 feet from the end of the boom where the main sheet attaches, and figured that''s how far forward the front edge of the bimini will reach. I measured 3 feet forward from the boom end and figured that''s where the mounting brackets would go. I measured the coaming width there, and swung the boom out over the coaming (with the sail still hoisted) and measured the clearance between the bottom of the boom and the coaming at the expected bracket location point. Most bimini frames can be shortened somewhat by cutting the main section tubing; this is what I''ve done to mine to get the right height. Unless you''re buying a do it yourself kit like Sailrite''s, the width of the bimini frame will not be too adjustable (but they do have different style mounting brackets that can go on horizontal, vertical, or canted surfaces). I''ve even seen folks put brackets on the jib block sail track which allow them to slide the bimini back or forward when folded up.
Allen "Made in the Shade" Flanigan
SV Norma June