Dear Parker 27/275/285 owners,

do you know if you are getting the best out of your boat in all points of sailing? How do you measure your performance? I pick a boat that sails well and compare my performance to it. A good indicator but not great.

Today, boat designers create a polar model that predicts the performance of a boat on all points of sailing for various wind strenghts. Owners then use these diagrams to see if they can drive the boat to its potential. It’s very useful particularly if there is no sister ship racing in the fleet as now you have the facts to compare against your performance. It is also useful for cruise planning as given a forecast you can more accurately predict your arrival time at your destination.

Unfortunately, polar models were not around when the Super Seal was designed. All is not lost however, as Ron Holland Design are willing to create a polar model for the Super Seal which will also apply to Parker 27/275 and approximate the Parker 285. There is one snag, the cost of €1,000 (this is before negotiations!).

I have suggested to the Commodore, Mr Clifford Miller, that the Association negotiate with Ron Holland Design to produce the polar model and then publish it in the handbook or sell it at a reasonable cost to the Association members. If there is sufficient interest and commitment to purchasing the polar diagram to cover the cost, I feel that the Association would fund the development.

If you are interested please post a reply to this message. If you have any questions on polar models I’ll do my best to answer them.

Some WEB sources on Polar Diagrams and Velocity Prediction Programs, VPP (don’t be put off by the TLAs and the hard sums, the diagrams are easy to read):

http://www.c34.org/faq-p...s/faq-polar-diagram.html 

http://www.sailinganarchy.com/YD/2003/vpp.htm 

A very good book on sail trim (the best book so far in my humble opinion) is North U TRIM. It has a section on polar models and VPP.

The email I received from Ron Holland Design follows.

Regards,

Donal Gleeson

BTW: TLA=Three letter abbreviations!

-----Original Message-----

From: Ron Holland Design [mailto:info AT ronhollanddesign.com]

Sent: 08 September 2006 17:10

To: Donal Gleeson

Subject: Re: Super Seal 26

Donal

When we designed the Super Seal, we did not use polar comparisons. We

could create a polar model for this design for a fee of EUR1,000.

Regards

Ron Holland

--

Ron Holland Design

28 Lower O'Connell Street

Kinsale

County Cork

Ireland

T. +353.21.4774866

F. +353.21.4774808

E. info AT ronhollanddesign.com

W. www.ronhollanddesign.com 

Skype ronhollanddesign

Donal Gleeson

seems absolutely pointless to me, it can only predict its performance and there are far to many parameters effecting the performance of each individual boat.

try racing its cheaper and you get a real world look at the performance of you and the boat.

sean

Racing against a sister ship will show your strong points and weak points against the other boat and would be the preferred way to tune the boat and crew. I used to race Enterprises and analysing your performance was very clear cut: your finishing place. Unfortunately I rearly get to race against Super Seals and Parkers so I do not have the opportunity to measure the performance of the boat.

I agree there are many factors affecting performance and the model is only a prediction. I would argue that unless you know the potential of a boat in various points of sailing how do you know you have got the trim/tuning of the boat correct? (being in front is a good indication I hear you say!).

Where I see the polar diagram being useful is in pre-season training and training between races. Typically you will be out sailing without other boats to compare your performace against. The polar diagram/model will allow you to assess the performance of the boat and will indicate where improvements can be made. I view the polar model as just another tool in the box to help you get the most out of your boat.

Thanks for the input.

Regards,

Donal

donal gleeson

RE--the 27 --I have done alot to gain performance-- replace the sheeting sytem with a travler-- (careful to suport boom) replaced rigging--- changed roller system and length of forestay etc.

I have tried many different sails spectra--kevlar and now have settled on dacron as my choice for overall.

I have more mast sweep now--about 6-8 inches that is faster

My keel is smooth and bottom smooth but all shapes are same except for base of keel where I finished more fin like.

Finally--I visited Bill Parker at his shop in UK and found a wonderful trick---play with the rudder sweep back. I run a straight edge down the transom and measure. Also--finsh the bottom of the rudder--fin like. A few others have discussed this elsewhere--

Ask Bill Parker what he suggests and get back to me on that one. You will be surprised.

Marv

PS still need help with keel strop wire

Marvin Kowalewski (USA)

---

sorry,

i had not forgotten about the keel strop length, problem is my boat is on the hard and the keel strop is jammed by the keel and i cannot lower the keel until it is back in the water

sean