Tipping angles

[All U Get]

Hi all,

The first trip we took on the ICW we tipped our boat to get under a fixed bridge. I can’t find my calculations from then, so if anyone is interested I’m looking for the heel needed to tip a 65 foot mast to 63 feet in height (round numbers for this calculation)?

Back then I wrote 10 degrees, but I don’t know if that was accurate. Pearsons are very stiff and I only got 6 degrees at that time.

 

[Davidasailor26]

The geometry part isn’t so hard -

When you induce heel you’re making a right triangle, where the mast height is the hypotenuse and the heel angle is adjacent to the net height.

The cosine function tells us the net height (x) is 65 times the Cosine of the heel angle.

To solve for heel angle you need to reverse the equation: angle = inverse cosine (63/65).

By that math the angle needed would be 14.25 degrees.

The trickier part is knowing whether the model’s approximations are accurate. For example, does the boat really pivot right around the point where mast would intersect the water? Does the hull shape change the buoyancy either up or down making that point higher or lower?

 

[All U Get]

The geometry part isn’t so hard -

When you induce heel you’re making a right triangle, where the mast height is the hypotenuse and the heel angle is adjacent to the net height.
View attachment 200447

The cosine function tells us the net height (x) is 65 times the Cosine of the heel angle.

To solve for heel angle you need to reverse the equation: angle = inverse cosine (63/65).

By that math the angle needed would be 14.25 degrees.

The trickier part is knowing whether the model’s approximations are accurate. For example, does the boat really pivot right around the point where mast would intersect the water? Does the hull shape change the buoyancy either up or down making that point higher or lower?

In the middle of the night I remembered using the 63 for the leg on the right triangle, then 65 for the hypotenuse. Six sailors standing on the starboard rail and dinghy on the boom to starboard only got 6-8 degrees of list. I’ll need more weight.

 

[Will Gilmore]

In the middle of the night I remembered using the 63 for the leg on the right triangle, then 65 for the hypotenuse. Six sailors standing on the starboard rail and dinghy on the boom to starboard only got 6-8 degrees of list. I’ll need more weight.

Hang a large trashcan by a sturdy harness attached to your halyard. Mark your halyard at 60' and swing the can over the side into the water once you've heeled the boat over. Haul on the halyard once the can has filled with water. Use the dinghy to keep the can from swinging aft as you lean and move forward. You should be able to estimate your actual height without calculations, from masthead to trashcan.

-Will

 

[RoyS]

Buy a new Windex.

 

[thinwater]

The calculations assume that the hull is a cylinder and that the center does not rise as it leans onto the rail (like a scow or a catamaran rise when heeled). You probably need to heel a few more degrees than the simple trig calculation suggests.

Wouldn't it be simpler to go outside?

 

[Tom J]

When we transited the Okeechobee Waterway, we needed to heel to clear the railroad bridge at Port Myaka. A guy from Indiantown Marina met us at the bridge, and strapped two water barrels to our side deck. He hung a line with two steel nuts tied on to mark the desired air draft from the mast, and then filled the barrels with water. When the nuts touched the water, he told me to put the boat in gear and proceed under the bridge. Very simple and effective method.

 

[jssailem]

Tom, your experience sounds a lot like the one demonstrated in this youtube video.

 

[Hello Below]

It's time like this when I ask myself the question: "If things go bad should I really expect my insurance to cover the cost of repairs if I (insert intended action)?".

 

[All U Get]

The calculations assume that the hull is a cylinder and that the center does not rise as it leans onto the rail (like a scow or a catamaran rise when heeled). You probably need to heel a few more degrees than the simple trig calculation suggests.

Wouldn't it be simpler to go outside?

We did 1000 miles outside, now we’re going to a marina that isn’t silted in awaiting dredging. Had a chat with a local while doing a fuel run. They have had shallow spots in the entrance and can’t afford to have a deep draft boat stuck blocking traffic. Four years ago we were able to get in at high tide. Mother Nature is in charge.

 

[sailme88]

Put 4 of those 6 guys out on the boom....

 

[jssailem]

On the Boom? They likely will fall off now you have a rescue while stuck under the bridge.
Life is crazy that way.

 

[All U Get]

Put 4 of those 6 guys out on the boom....

Or one Mainer.

 

[sailme88]

Or one Mainer.

that would be a BMW....

 

[All U Get]

We made it under the bridges in Vero Beach at low tide. A friend took a dinghy over to check the tide board for us about one half hour before low and said it was 64.5 feet. We have no problems with that amount and were already getting near the 17th street bridge. It’s sign board read 64+ which we know has been in error for many years. The bridge nearest the marina had the proper height of 64.5. They were both less than 63 last week. Now I can rest.

 

[RoyS]

Is it OK to run your engine with the heeling angle?

 

[dLj]

Is it OK to run your engine with the heeling angle?

Typically that's what's done...

dj

 

[jssailem]

Is it OK to run your engine with the heeling angle?

You will want to keep the engine raw water inlet beneath the water line while doing this. It may dictate which way you have to lean...tip the boat.

 

[All U Get]

Is it OK to run your engine with the heeling angle?

If that thru-hull is out of the water, you will have bigger problems than tipping.

 

[RoyS]

How about the oil pick-up inside the engine? Will it be pumping air instead of oil? Best to check with the engine manufacturer before attempting this procedure.