Rudder rake as it relates to mast rake and trim.

[Pylasteki]

Hi guys. I've been pondering the relation of raked keel hung rudders to mast rake.

My Triton has a rudder that is raked 50 degrees from the designed load water line. 30 from the bottom of the keel... The common fix for excess weather helm is to rake the mast forward. Most Triton's are float 4 inches lower in the water than what the stock plans call for. (6400lbs designed vs displacement of 8000.)

I'd like to get some other opinions... Does raking the mast forward push the bow down as the wind pipes up? I'm wondering if the rake trims the bow down under sail.

Weight in the stern of most of Alberg's designs is a major no-no, as the speed drops off and the tiller to your navel going to windward...

Are all these things related? I'm trying to work out where to put some heavy stuff (Galley, Batteries and tanks, tool box...) and thinking it may not be a bad thing to trim the stern up where possible. (Besides, they don't look so hot when squatting... )

My understanding is that the more rake the rudder has, the less effective it is... so standing it upright should make it more efficient at turning the boat?

Thanks for your thoughts guys...

Zach

[Steam Flyer]

Originally Posted by Pylasteki

Hi guys. I've been pondering the relation of raked keel hung rudders to mast rake.

My Triton has a rudder that is raked 50 degrees from the designed load water line. 30 from the bottom of the keel... The common fix for excess weather helm is to rake the mast forward. Most Triton's are float 4 inches lower in the water than what the stock plans call for. (6400lbs designed vs displacement of 8000.)

I'd like to get some other opinions... Does raking the mast forward push the bow down as the wind pipes up? I'm wondering if the rake trims the bow down under sail.

Weight in the stern of most of Alberg's designs is a major no-no, as the speed drops off and the tiller to your navel going to windward...

Are all these things related? I'm trying to work out where to put some heavy stuff (Galley, Batteries and tanks, tool box...) and thinking it may not be a bad thing to trim the stern up where possible. (Besides, they don't look so hot when squatting... )

My understanding is that the more rake the rudder has, the less effective it is... so standing it upright should make it more efficient at turning the boat?

Thanks for your thoughts guys...

Zach

That's right.... the more upright the rudder is, the more effective.

Raking the rudder post forward might help leep flow over the upper sections of the rudder as the boat heels, but not sure about that and 50 degrees would be too much anyway.

There is no design correlation between mast rake & rudder rake that I've ever heard of... not that I know everything

Generally, bow-down trim is worse than squatting. Bow-down will increase weather helm and reduce initial stability. For many hull forms, it is good in light air because it reduces wetted surface area (and you don't need stability as much in light winds). OTOH be sure where your trim really is. People sitting in the cockpit do put the stern down considerably, and you want to trim the boat for sailing rather than sitting at the dock.

Raking the mast forward... doesn't push the bow down any more than not AFAIK, it kills your pointing upwind and is fast downwind. Set the mast rake for good helm balance and don't worry so much!

FB- Doug

[Pylasteki]

Doug,

Thanks for your response. I've been noodling through this boat and keep finding questions that I don't know the answer, and no book really covers.

Yeah, mainly I'm interested in figuring out if weatherhelm is reduced by the moving of the center of effort forward... (Which would be what... inches?)

Or if its somehow pushing the hull shape around.

I get accused of thinking to much all the time. All I can say... I'm an addict!

I've been studying the line plans of the Triton, and stock they don't sit on their designed LWL, and so now I'm wondering if they are trimmed according to the line plans. I'm chasing my tail trying to figure out how the hull was intended to trim, so then when all the weight of added batteries and tankage goes in she'll be true to form. They aren't exactly known for their docile helm...

Just hoping if I kick over enough rocks I'll stumble over something cool.

Thanks again!

Zach