bow weight

[Franklin]

With a chat with a neighbor sailor, he mentioned something about a chat he had with a boat builder about his weather helm problem. The boat builder told him to add 450 lbs in the bow. Said the bow was too light and that was the major cause of the weather helm. He said he added the weight and the problem went away.

Now I am fully aware of the problems associated with a heavy bow, but does having weight moved forward reduce weather helm? I guess now that I think about it, if the keel is the swinging spot, then weight forward would push it down when heeled and beating. I wonder if this is why Hunter puts the water tank just behind the anchor chain locker? So that the weight up there can be changed depending on the sail?

Do all the other production boat makers put the water tank forward these days? I know the older boats put them midship.

 

[Franklin]

Well, nevermind that. Everything I read says the opposite. Move weight aft and windward side to raise bow and move clr aft. Just as I remembered. Weight aft when going to weather and weight forward when running so not to drag stern.

 

[Franklin]

Ok...this really has my mind wondering around a bit

All the writings about weight talk about weight forward moves the CLR forward which increases weather helm. Ok...I kind of get that, but....it also moves the CE forward as well which the writings do not talk about. The CE moves forward because as the bow goes down, the mast head goes forward almost 5 times as much. That is basically the same thing as reducing rake, which of course reduces weather helm.

Now I know that big time racers load up the crew on the rail starting at the stern keeping the weight aft as much as possible when going to windward and the racing industry is a multi-billion dollar industry so they have to be right, right?

 

[Will Gilmore]

Times, they are a changing. Boat designs too. They have less rocker, sterns are wider, overhang is almost nonexistent, now. The newest boats are more wedge shaped than gently tapered ovoid shapes. New boats are wider and keel shapes are deeper and narrower while sails are doing the same thing with large headsail.
All this means the changes in hull trim may have different effects on new designs' performance than traditional older designs.
In general, while sailing dead down wind, too much weight forward means the stern becomes easier to push around while the bow digs in. With following rollers, steering becomes very difficult. Everytime a wave lifts the boat she pivots on an axis farther forward while the bow drags but the stern doesn't.
When designing for CLR versus CE, the CE is set a proportional among ahead of CLR to begin with. As a boat heels, the waterline shape changes. As the winds push/pull on the sails, the CE also moves outboard to leeward while the deeper keels' frictional resistance moves to windward. This contributes to weather sailing. Other factors include flattening sails with less lift but more resistance so more heel. Then, the keel has a lift effect also. However, as the boat heels more, it spills air and limits the heel.
A modern wing keeled boat sails hard on the wind with plumb bow digging hard into the water, the wide stern means double rudders are needed, but center keels lift out of the water, so you see dagger boards near the outboard line while the kanting keel is used purely for ballast instead of lateral resistance. Move weight forward here and the bow contributes more to lateral resistance. The wedge shaped hull now has an in water "keel line" that is aimed into the wind and an asymetrical shape that wants to turn her more into the wind. The sails CE moves ahead, but it also moves way outboard of the centerline. This gives it a longer lever arm to pull on with the center of resistance in the water as the axis point. The natural tendency of a sailboat is for the weather helm to increase as she heads closer to the wind in heavy conditions. (Light conditions where less heel is induced, that is not the case). Moving weight aft should help reduce weather helm.

If there is a lot of rocker and a broad mid ship shape with tapered ends, heeling into the wind may tend to bring the bow out of the water as the in-water shape remains relatively symmetrical. This would mean weather helm may disappear as the boat heads into the wind. Weight forward would rock the hull forward, but, while heeling hard, have little effect in moving CE forward because the axis angle is no longer in line fore and aft over the keel line.

Whew, I think I've lost track of where I am, so I'll leave it here.

- Will (Dragonfly)

 

[Joe]

Ballast placement has always been a big part of sailboat performance.... back in the "age of sail" the cannon, cannon balls, ballast iron, cargo, water barrels, etc. made up the ship's ballast and were commonly stowed in particular places to enhance the vessel's speed or stability. It was not uncommon to shift the ballast around to compensate for depleting stores as the voyage progressed... or alter the ships performance in extreme conditions.

The crew can also be considered part of a sailboat's ballast...

 

[Will Gilmore]

The crew can also be considered part of a sailboat's ballast...

Absolutely.

The "Great Age of Sail" also suffered from poorly secured ballast. Early on, the bilge might have been filled with stones to ballast the vessel, but they were left loose and a hard blow with large waves would cause them to shift. Of course, they never shifted to a better spot, always to the leeward side, for some odd reason. Then, sinking ensued.
I think it took them awhile to figure that one out. First they needed survivors, then they needed survivors who know what happened, thirdly, thy needed survivors that knew what happened that they were willing to listen to. That last criteria was the hardest one. Read up on the history of scurvy in the British Navy and you'll know what I mean. they went for over 75 years not employing a known and proven prevention for scurvy because no one liked the man who discovered the use of citrus in preventing scurvy on board ships.

-Will (Dragonfly)

 

[dlochner]

As Will alludes to, hull shape and point of sail determine optimal ballast/weight placement.

What kind of boat are we talking about?

My boat has a large (40 gallon?) water tank in bow , the Sabre 30 had a 20 gallon holding tank in the bow.

 

[TomY]

Yikes, adding 450 pounds of weight to any sailboat that will carry it, will make a difference in performance.

"Weight is the enemy" Bob Perry. That's a sailing mantra I live by. Many cruisers are deluded when it comes to the weight on their boats. Could be where the saying, "I don't sail at less than 4 knots", comes from: Their boat won't move in less than 10 knots of wind.

Racers on the other hand, wouldn't even think of adding pounds unless they could use it to their advantage (like on the rail).

I'm somewhere in the middle. I love to sail. We have a third, 40 gallon water tank under the vee berth. That adds about 350 pounds and I can see it lower the trim at the bow, by 3 or so inches. Needless to say, unless we're leaving for few weeks, it stays dry.

I'd find another solution, like remove weight, if weather helm could be reduced (I doubt it).

 

[Will Gilmore]

with Tom.

The real advantage to water under the 'V' berth is it keeps it centered port and starboard and it isn't in the living space. If you really need to add weight forward, consider going to all chain anchor rode. Then, at least, you can justify it with a savings in scope and swing radius at anchor while improving safety. It also takes up less space than a water tank.

- Will (Dragonfly)

 

[TomY]

with Tom.

The real advantage to water under the 'V' berth is it keeps it centered port and starboard and it isn't in the living space. If you really need to add weight forward, consider going to all chain anchor rode. Then, at least, you can justify it with a savings in scope and swing radius at anchor while improving safety. It also takes up less space than a water tank.

- Will (Dragonfly)

Good idea! There's no better way to go bow down, than to add an all chain rode.

 

[Kermit]

You need 450 lbs. of weight? You could ask my ex-wife to lie in your bilge, bow, water tank or even your waste holding tank (where she really belongs). Nah, I’m pretty sure you’d be better off with weather helm. Or even lee helm. Or smashing your boat into a lee shore. At night. In a hurricane. With no hope of rescue.

 

[lillia28]

I would also consider the possibility that the boat builder was speaking about a specific boat or boat design that may have needed additional weight in the bow, not as a general solution to weather helm. I have always heard that excessive weight in the bow leads to hobby horsing, but if the bow needed 450 pounds that weight wouldn't be excessive. And 450 lbs would have a different effect on a 25 foot boat than a 65 foot boat, so I am thinking there is more detail to this story.

 

[Roadking Larry]

Ballast placement has always been a big part of sailboat performance.... back in the "age of sail" the cannon, cannon balls, ballast iron, cargo, water barrels, etc. made up the ship's ballast and were commonly stowed in particular places to enhance the vessel's speed or stability. It was not uncommon to shift the ballast around to compensate for depleting stores as the voyage progressed... or alter the ships performance in extreme conditions.

The crew can also be considered part of a sailboat's ballast...

Ballast and trim still plays a big role in submarines. A full load of stores for a 3+ month "cruise" could seriously change the static trim of the boat. Fun thing to do with a newly qualified Diving Officer was to get 8-10 guys and form a trim party. All of them get as far in the bow as they can get, after the DO compensates for that they all lay as far aft as they can get, repeat till board with it.

 

[thinwater]

The rather obvious answer, which every racer knows, is that you move crew around to see what she likes. They also know that up wind and down wind are different, ad light air is different.

 

[Crazy Dave Condon]

Before going any further, @Franklin needs to advise which boat it is as a simple adjustment on the mast might resolve the issue and where and under what conditions

 

[Franklin]

Sorry fellas, I thought the thread died. The only thing I can add is that I believe it was an old boat. It did sound strange to me and I'll just put it in the 'Odd things I heard people say' file and forget it. I do know that when my tank is full, I sit just about level with the water line on my boat and that includes 10 jugs on the foredeck, 200' all chain in the locker and a 45# anchor, but I think it only changes about an inch between full and empty.

 

[jssailem]

By “Level” do you mean the boat is resting on the water line that is painted on the side?
Some water lines are meticulously calibrated and painted with care... Others are an approximation of what was on the boat and sometimes drift up or down based on the care of the painter.
Unless your going to verify the boats designed water line, what is practical is how you see the boat preform based on what you load on the boat and what the water conditions are you experience.
Cruising and racing activities set up different conditions. Different boats will have different water lines/contours. They will react differently as you move weight around. The balancing of your boat in the conditions you are facing is one of the skippers jobs with which many are not proficient. Thus the opportunity for sailors in a marina to share wisdoms... Yes. Pack a bunch of chain in the boat bow and you will solve your weather/lee helm problem.

 

[Franklin]

My water line is exactly what the manufacture put on the boat. That I know for sure and I do believe Hunter did a good job on the placement of the water line, leaving lots of room for loading the boat down, so I believe it was carefully measured and painted. And yes, the interior is level as well, matching the water line. After living on my boat for 12 years and sailing her for 13 years, I'm pretty sure I would know if it wasn't right.

 

[Crazy Dave Condon]

I am on a cell phone so I cannot tell which boat

 

[Davidasailor26]

I am on a cell phone so I cannot tell which boat

Hunter 376. Put your phone sideways to go to landscape mode and it should show you the profile info including boat type.