Lee Helm on my Olson 34

[Loren Beach]

So another question to Olson 34 owners - does the mast have any angled mast base or anything under the mast to tilt it backwards ?

Do you use any specially designed wedges where the mast comes through the deck to push it backwards ?

Our mast base fits flat, on top of a wider "hat section" glassed-in stringer.

When I removed the original molded vinyl "boot" for the mast penetration thru the cabin top, I found 4 wedges. The front and back ones were carved into matching curves in teak and there were a couple of short side ones. As I (dimly) recall, my spar was much closer to the front of the FRP-molded-in-collar in the housetop. Not being much of a wood carver, I made up a piece of teak in an L shape, to give it a "shoulder" to keep the future wedges from falling thru, since they fill in a parallel open between spar wall and FRP molding, and then cut them into sections about an inch long. The front ones, having allow for the curvature were maybe a half inch wide. I equal spaced the gap all the way around. Come to think of it, I probably induced a little weather helm... since the spar was closer to the front of the opening when I first got the boat. Hmmm......
Oh well, a little weather helm is a good thing.

As to the step, I will have to try to get some photos. As I recall, it is the same Kenyon spar and cast step that I see on same-era Ericsons around here.

If you have the boot off the mast base, how 'bout posting up some closeup photos? Some pix of the base might be helpful, too. Admittedly getting a good closeup of the rear of the base would mean removing the table, the backside curved teak trim, and the center cabin sole halves. The forward part is easy to see by lifting out the teak drop-in trim piece.

I have been blathering on about "Kenyon" because that was the Ericson (and Olson) spar maker thru the mid-late 80's. Is that in fact what your boat has?
After all, I know of at least one Olson in California that was retrofitted with a Ballenger spar. www.ballengerspars.com

Regards,
Loren
ps: edit to add photos showing front of spar foot -- note that the stock base casting has no provision for fore n aft movement.

 

[Gary Schroeder]

Rake and Rudder

Simon,

I think you should keep that race record in mind and focus on tuning the rig before you alter the rudder. The stock may enter the top of the rudder at the 35% of chord point, but that's not what will effect the balance, because your rudder is not rotating around the "35% of chord" line, which is angled aft on your rudder. It's rotating around the centerline of the stock. It looks like most of your rudder is behind the axis of rotation (the red line) of the rudder stock. The offset between axis and the CE is what you're questioning, and it's hard to see that the sliver in front of the axis is going to pull the CE so far forward as to counter the area behind the axis.

Additionally, wedges under the foot of the mast will not rake it. They only affect the distribution of the compression load around the base the mast. You might need some because you raked the mast, but not to rake the mast. Rake is determined by where you position the head with the forestay, and where the mast is locked when it passes thru the deck. On your boat you can move the first, and probably adjust the second. Wedges at the deck can be a starting point for setting the rake & allowing for bend when you're installing the mast, but they're there to secure the mast at that intersection and enable a watertight (sometimes) (ever?) seal.

Bare in mind that all this pontificating is worth what you're paying for it, and if you need to see me about it, I have a funeral to go to that day.

 

[sjconnor]

Mast base and Rudder profile

Loren, thanks for your response. I don't have a table so its very easy, and I've attached a photo. Will try to see next time which mast I have. At least that puts my mind at east that I shouldn't be looking to install anything under the base of the mast to rake it back. I too had put in wedges in that deck hole to basically secure the mast from rattling around. With in-line shrouds it kind of implies (at least to me) that the mast is relatively vertical. I've been advise to tighten the shrouds too so that might bring the mast back slightly.

Gary, thanks for your insights too. Good point and made clearer by your photo modification, thanks for taking the time to do that.

For the rudder, I think when I had it repaired - ground down and re-laminated it likely lost its original shape somewhat and has increased the leading edge pressure. For example the widest part of the rudder profile is forward of where the rudder stock is. I imagine this would increase the pressure still further forward. See attached modified photo. I've seen from other profiles that the widest part of the rudder is at the pivot line, ie where Gary's first long line is drawn.

 

[ted_reshetiloff]

That step is adjustable too. Loosen everything up, all shrouds and the bolts on step and knock that base forward. Then tune the rig setting the rake at 6" to start. If its better but not best, ease the for stay a few more turns. You have a Backstay adjuster on that boat? Trick I found was to get the rake (balance) right for most prevelant wind conditions (5-10 here). Then with the rake and tension set right I could pour on backstay and it would initially take up the sag in the forstay, then start bending the mast flattening the main. It is the initial setting that take a lot of trial and error to get right. You dont want the mast to start bending too soon. You want the right amount of forstay sag, rake(helm pressure) and rig tension (mast not tipping to leeward and center in column). I'm guessing the PO can't give you the rig settings that he was using to collect all them pickle dishes with eh? You will need to probably do a lot of sail-tuning to get this right. Then measure everything and write it all someplace safe! One way to speed up the process would be to buy a new sail. If you do you can probably get the sailmaker to come sailing with you and help you get things tuned right.

 

[Charlie B.]

Olson 34 rudder dimensions

Sorry to jump in late on this thread, but I just hauled my Olson 34 out last week and took the opportunity to take some measurements of the rudder. Hopefully this will add to the information database in case anyone should lose a rudder.

Does anyone have the dimensions of the deeper replacement rudder?

Charlie B.

 

[CTOlsen]

mast rake

Sorry to have missed out on this discussion, I've been incommunicado for a while.

Loki has excellent balance- slight weather helm. This would suggest that it souldn't take much change in mast rake to create weather or lee helm.

You can understand helm as a moment created by the difference of the center's of area of your sail area vs your underwater area. If you move your sail plan forward, you create a moment which creates lee helm.

I would look to move the foot of your mast fwd, so as to move the top of your rig aft (rake). I adjusted mine by pulling up to a srysail hoist and lifting the mast a few inches in order to gain access to the butt. You'll have to also lengthen your head stay a bit.

Good luck,
CTO

 

[sjconnor]

The results after reshaping the rudder

You can see from the pics the comparison before and after. I chopped off 2 inches from the leading edge which now gives more like a 70:30 ratio of trailing edge to leading edge. The process followed essentially was one of trial and error. Reduce the leading edge, then sea trial. Upon sea trial 1 I found the boat to stear off center and concluded it was due to too much guessing on the profile and so the second round of reshaping was based on a template I made from the use of other diagrams that I'd blown up to scale. They proved very useful. The second sea trial resulted in slight weather helm. What a difference - to let go of the helm and have Sapphire slowly bear up to wind instead of going immediately into a jybe.
This was very satisfying. So I removed the rudder again and now its ready to be antifouled. I would say that all in all it was a successful modification. It took a few days of my time removing, refitting the rudder etc and supervising the work, and the reshaping of the rudder cost me about US$300. I also had to invest in a lycra body suit to protect me from the swarm of jelly fish we had during the past month or so. In the process I've also welded an inverted U fitting to the top of the Rudder stock to make refitting and removal that much easier.

Thanks again to everyone's advice. I may not have necessarily followed your suggestion but each one was taken into consideration and discussed before I proceeded with the course of action.