SO 39i seems slow under sail and power

[mbw9494]

Can anyone advise and comment please re, what appears to be the poor performance of our SO 39i owners version.
We purchased our 2007, 39 i recently she has in mast reefing and the original sails. The Main looks tired and may need renewing. Additionally she needs to be re anti fouled, the previous owner missed a season. All this said she seems slow for her size. A pal recently overtook us in his Westerly 33'.3''. It could be my poor sailing. But she also seems a little reticent to motor at 6 knots. Comments on how to improve performance would be much appreciated to remove our current disappointment in what we believe is a lovely boat.
Many thanks and regards.
MBW9494

[MalcolmP]

Welcome to the forum

You should be getting much better performance than that in my experience.

Presume the log speeds are being confirmed by GPS (accounting for tide etc) - the paddle wheel  and/or calibration may need checking

Agree first thing is to make sure the hull and rudder are clean and also the prop - there is a massive power-loss when barnacles etc are on the blades. Presume it is the original 3 blade fixed? if so should be good under power (but creates lots of drag when sailing - so I would think about a folder/feathering at some point).  I would expect than in calm conditions and no tide you should be able to get around 7 knots at 2300 or thereabouts - increasing the revs may increase speed through water slightly - but stern will sit down even more at max say 3200 you may get 7.5 knts.

I don't know much about in-mast furling, but clearly if the sails are stretched - there maybe little you can do to improve shape - might be worth speaking to a local sailmaker to see if any re-cut might help

Overall we remain very pleased with the overall performance of our shallow draft version - but think that overall performance is probably quite similar to the standard draft SO36i - we are not racers - but unless the Westerly was clandestinely motoring,  I am sure once you have checked the sails and the hull condition you should be able to significantly improve your speed both under power and sailing

I am sure others will be add their thoughts as well

Malcolm

[rc sail]

Ahoy MBW,
I have 2007 39DS and will give you some response as I believe we should have same hull for DS and i.
I have the factory fitted 3 blade prop. At spring launch with fresh anti-foul(inland Great Lakes and VC anti-foul) I easily do 7 kts at approx 2500 rpm. Late summer I will drop about .5 kt due slime build up on hull/rudder. I have in-mast main and I need at least 9 knots wind to get my DS moving at 5-6 kts or better.
I think the 39 DS or i have great hull design but a great loss of sail performance with the in mast furling.
Hope you can get sorted out to fully enjoy your Jeanneau.
rc

[rene460]

Hi MBW,

Malcolm and rc have given an idea on what you can expect so you are not imagining things, and it is a lovely boat.  I have an SO30i but three suggestions that apply to all sizes:

1 Check the rated speed of your engine in the hand book, or check it out on the manufacturer's website.  For my  Yanmar it is 3600  rpm.  At full throttle the correct prop should run perhaps 200 rpm faster, say 5%.  Then it will be better loaded at normal operating revs.  Before my last slip for cleaning, my engine would only do 3400 at full throttle.  On inspection there were a good(?) number of barnacles on the hub.  But the blades were clean.  Now after cleaning 3800 rpm.  A previous occasion when the engine would not achieve full revs a single barnacle was found on one blade.  Boat was much slower than normal for given revs, and max revs not achievable.  Only one barnacle! When it was removed performance became normal.  With correct max revs, engine load is appropriate and boat speed will follow.

2 Check the hull.  Not much weed and slime will slow you quite a bit.  If you are not keen on diving, there may be someone in your area who will brush down the hull in the water, it makes quite a difference, but if you have not slipped recently, it is worth doing properly for the peace of mind of a good inspection clean back and replace anti fouling and check anodes for another year of worry free enjoyment of your boat.

3 Check out your sails.  Tired old sails cause slow, are difficult to trim for flowing tell tales, cause difficult steering and rounding up in gusts.  First take photos up from boom and deck level and talk to a sail maker.  You may be asked to bring in the sail for better assessment.  A recut of the luff may help and is worth trying, but it is hard to beat new good quality cloth and good shape cut and sewn in.  Not worth major recut of bad material and old stitching.  New sails from a good sail maker are a bigger bite, but the joy of new sails that will set and trim easily and allow the boat to nearly self steer in the groove is hard to beat.  Like a new boat!  Worth looking at the sail area of the Westerly compared with weight and length of hull as your in mast reefed sail may be optimised more for higher wind strengths, particularly if you normally sail in lighter wind.  Your pal may have a relatively larger sail area especially if he has a big
overlapping genoa.

rene460

[mbw9494]

Hello Malcolm, R.C. and Rene 460
Thanks for taking the time and trouble to consider the issues I am experiencing with my SO 39i.

The boat comes out of the water mid October so once she is dry I will carry out a thorough sanding down and antifoul etc.

The Southampton Boat Show is next week so I will start inquiring about a possible new main and folding prop. Whilst there I will also check out the cost of a Spinnaker or Cruising Chute . Not sure which is best as it's only me and Barbara that do 95% of the sailing.

Thanks also about engine / prop advice. I had no idea the difference a little barnacle could make to a 39 ft both weighing a few tons!
Happy Sailing
MBW9494

[MalcolmP]

Hi MBW

I will be at the Boat Show as well on several days - I will be on or around the Bruntons stand G071 in Ocean Hall - whilst I am biased over Brunton props - the guys on the stand should be able to give you some honest advice on pros and cons even if you don't buy a Bruntons (they are not the cheapest) - there are quite a few threads on folding - fixed - feathering on this forum that you may want to search through.

Re a cruising chute - we have one in a snuffer that just Eileen and I set - it is great for a long reach, but does take quite awhile to set up - with hindsight I think a code zero or similar set up on removable furler would have been better and get more use. I saw the extreme 40 cats racing in Cardiff the other week and the speed that the furlers of setting and retrieving light weight sails is really impressive 

Would be interested how your research on a new mainsail goes - I am thinking next year I should also take the plunge and invest also

Malcolm

PS if any other forumites are around at Southampton - I will be there this Friday and Saturday at least - do call by the Bruntons stand or give me a call 07810 594732 always good to see other Jeanneau owners

[mbw9494]

Hello Malcolm P.
Thanks I will check out the Bruntons stand on Tuesday and seek their advice and hope to see you there.
Regards
MBW9494

[heelingpower]

Our 39i is the performance model prototype launched 2005 then refitted 06 as 2.2 draft performance. Wehave had the boat from new in new Zealand. the first year the local dealer had put a fairly light coat of antifoul on and whilst looking fairly clean the slime slowed us up to maximum of 5 to 6 knots after about 6months in the water. we now get regularly 20 to 26 months from well applied altex ablative paint. speed is 8.4knots flat out digs the stern in and drinks diesel. otherwise we tend to motor at 1800 to 2300 at 5.5 to 6.8 knots . we have Volvo 3 blade prop.
we did add 450mm to the boom when we fitted a leisure furl roller furl boom ,got a good performance gain with the extra sail area
regards
brett

[mbw9494]

Hello everyone.
Thanks for all the advice. She is out of the water and ready for a good scrub down and a decent antifoul. We have purchased a new and better spec.s main for next season and are now saving up for a folding propeller.
All the best.
MBW

[MalcolmP]

Nov 13, 2013 9:36:33 GMT mbw9494 said:

Hello everyone.
Thanks for all the advice. She is out of the water and ready for a good scrub down and a decent antifoul. We have purchased a new and better spec.s main for next season and are now saving up for a folding propeller.
All the best.
MBW

Which sailmaker and spec did you choose? I am probably doing the same this winter

Thanks Malcolm

[mbw9494]

Main sail I chose , Cruise Premium  in Vectron due to it's suitability for in mast rigs, with 3 short leech battens to improve leech and sail shape, from Kemp Sails Wareham 01929 554 308. Got 15% off as a  Southampton Boat show deal. Hope that helps.
Regards
MBW.