Bimini damage caused by boom

[Gypsea Wind]

I will definitely check the rake before cutting anything. Thanks for the tips.

[DaveC426913]

All kidding aside, ck your mast rake, should be 1-2 degrees raked aft. More than that will cause your boom to hit your bimini.
Rake your mast aft just enough to let the boat head up to windward in a heavy gust.
You don't want a lee helm in a heavy gust as this will fall the boat off, creating more wind on the sails. lee helm is from mast being to straight. Why the Mac. has a 1-2 degree rake aft.

Under sail, my boom is well below the bimini, pretty much at nose-level when helming. I can't imagine any amount of rake would put it above the bimini.

How do you measure rake angle on a curved mast? From step to masthead? Or simply the angle that the mast makes to the step?

[March]

A curved mast denotes problems. Because of the lip and the groove for the main's slugs, a mast shouldn't curve all that easily--it may flex a little, granted, but that's all.

I never measured the rake but if I were to, I imagine that a line with a lead weigh attached to the top of the mast will give you a vertical, plumb straight down. Then you could use a horizontal leveller with an air bubble, once the boat is stable on the trailer and not on bouncy waters. You could easily figure out the angle between the two.

[Wind Chime]

To stop your boom rubbing and damaging your Bimini, have you thought about installing a BoomKicker.

We have one - and among other things, it holds the boom off the Bimini regardless of sail shape. Actually it creates better sail shape in light wind because the weight of the boom does not flatten the sail.

http://macgregorsailors.com/catalog/pag ... /index.php

[innervations]

Can I ask how you negotiate the boom kicker when lowering the mast? Does it detach easily?

[mastreb]

Can I ask how you negotiate the boom kicker when lowering the mast? Does it detach easily?

The fitting to the boom is a slide--push the boom up, and the fitting slides off and the boomkicker drops off, staying attached to the mast foot, and you can take the boom off as per normal. You can easily secure the boomkicker along the mast with the gooseneck or a small bungee, or you can take it off the mast foot by removing a clevis pin. I've done both when trailering. It's a minor complication.

Matt

[DaveB]

Sorry was away from puter past two days.
Appears your Bimini is way to high for boom to clear the Bimini while sailing. How do you sail at all with Bimini up?
Sounds like you have a Bimini way to high to sail in.
Do you have pictures?
Dave

All kidding aside, ck your mast rake, should be 1-2 degrees raked aft. More than that will cause your boom to hit your bimini.
Rake your mast aft just enough to let the boat head up to windward in a heavy gust.
You don't want a lee helm in a heavy gust as this will fall the boat off, creating more wind on the sails. lee helm is from mast being to straight. Why the Mac. has a 1-2 degree rake aft.

Under sail, my boom is well below the bimini, pretty much at nose-level when helming. I can't imagine any amount of rake would put it above the bimini.

How do you measure rake angle on a curved mast? From step to masthead? Or simply the angle that the mast makes to the step?

[bartmac]

We installed a Kicker and moded our biminis height to suit.....would not entertain sailing with out sun protection

[Dimitri-2000X-Tampa]

I'm not so sure about the sail shape comments here and wonder if you guys are putting your main sails all the way up? I do happen to have bad damage on my bimini as well but as with all the damage on my boat, it was mostly caused by the original owner who apparently didn't have a clue on a lot of this kind of stuff. Since then, I adjust my topping lift so that even with some downward pressure on the main sheet (boom secured for non sailing), it does not rub the bimini. I have the original dealer installed bimini like a lot of other folks have.

When sailing, my topping lift is very slack, which means that the boom is even higher than the aforementioned position, giving even more clearance to the bimini. And btw, this comment is based both on my original stock mainsail and the new mainsail I got from Judy last year, they are both cut prettymuch the same from what I can tell. In your defense though, I have raised my hounds a few inches to get the mast straighter, I am on the second to top hole of the shroud adjusters now...and there is still too much rake in the mast. So, if your mast is raked back even more, it could be different than mine. You may want to make sure that your boom vang and sheets are off when you raise the main, just in case it is not going all the way up.

[Gypsea Wind]

The Boomkicker looks interesting.

My Mac is on a trailer at home for the winter. Has anybody figured out what "level" is as it sits on the trailer? Bow to stern of course. Is there somewhere I should place the level to get it right before I start messing with things. I am wondering if the stripes at the bottom should be level as they seem to be pretty even with the water. I made the neatest A/C bracket to fit in the companionway last fall. Worked great on the hard, but after I launched it, the angle was wrong and it drained into the cabin! Anyway, finding level on the trailer may help some of these projects go smoother.

Bryan

[yukonbob]

I'd be checking 'level' on the water as a lot of things will determine 'level', ob size, weight distribution and so on. When I re-did the galley I slopped the countertop by a 1/4 inch so when on the water it sits ‘level’ as we tend to ride aft heavy.

[Gypsea Wind]

Check level on the water. Thats good advise. The only time I think of it is when its in the trailer. Doh!

[March]

I'm puzzled. Suppose that the boat is tail heavy on the water and the mast (that is supposed to sit perpendicular to the deck) is no longer vertical will therefore point backwards, at an angle of 5 degrees (or more). So how can measuring the angle of rake on the water help you figure out better the two degrees of rake?

Seems to me that, in the long run, it's the angle between the mast itself and the deck--in which case, measuring it on the dancing waves will add an element of excitement, but not necessarily of precision.

The table example that Bob offers is different: you need a horizontal surface so that things don't slide off the table. The rake of the mast is something else (I think?...)

[seahouse]

For proper sail shape, some mast pre-bend is required, meaning that normally the mast should have some curve in it to start. Increasing mast bend from that point (more easily done with an X than an M) will flatten the upper sail for high wind conditions.

Mast bend and rake are set as part of rig tensioning. On my M, I set it and leave it there, including mast bend, because there is no back- stay. Too much of either on an M will increase friction on the mast pivot bearing.

For the purpose of measuring mast rake angle the datum line for "horizontal" is the boot stripe, which does not change, whether on the trailer or in the water. Boats are designed that way - "level" will change with the sailing, and other, conditions.

When setting rake, putting the weight on the line in a pail of water will dampen the swinging and make the job easier. Then use trigonometry to calculate the distance from the mast for the angle you want. Too much and you will find you need too much rudder input to counter it (= "weather helm").

I would NOT cut any tubing on the Bimini or dodger (unless it's otherwise poorly made) until you have exhausted all other possibilities.

- Brian

[yukonbob]

Sorry, I didn’t realize you were asking about the mast rake. I just raise the mast and shoot for the 1 inch of mast bend. Unless you start shimming up the mast base it should sit perpendicular to the boat, I then use my topping lift and pull it tight to the mast base to see how much bend is in it. Too much, slack it off and adjust the shrouds, too little tighten them.