LM27 how to sail faster

[oceandancer]

Hello all,

No new posts at present so I thought I would like to start a new discussion thread !

I have an LM27 so some of my points are specific but most apply equally to all LM's. Come on all you pundits and lets have your ideas on how to make your boat go faster. Some would say that the LM27 is a bit challenged in the sailing department being bluff bowed and not close winded due to the rigging attachment points and then there is the keel , or lack of it. Well I don't believe it's that bad and in the right conditions it's quite quick.Here are my candidates for better sailing, what do you think?

1.  Clean bottom. Above all I believe this to be the most important item. But how to achieve it!  The lift and scrub where I am berthed is quite cheap but you wouldn't do this very often. I have thought about buying one of these new angled brushes - "Scrubbit" I believe they are called but used too often wouldn't this rub away the antifoul prematurely ?  Has anyone got one and can offer their experience and thoughts?  Perhaps frequent use of the boat is the best solution.

2.  Sail Upright!  The LM27 is , and I quote "an easily driven hull" but this is with no heeling. When you heel you dip that curved lea side into the water and create in effect a rudder on the bow which turns the boat sharply to windward. If you use a lot of tiller to counteract this you are only creating drag. Reef early and stay upright. The boat will sail fastest with the tiller nearly central.   Any thoughts?

3. Trim. The LM27 has a lot of reserve bouyancy but all personnel will be in the cockpit and she will be down by the stern when sailing with
extra drag. I like to ballast my boat by the bow with all heavy and unnecessary gear up in the forepeak lockers. Does any body else do this?

4. Shut the Lid. Yep!  I think that leaving the wheelhouse hatch open will slow you down ! Next time you are sailing on a port tack with the hatch open sit in the helmsman's seat and feel the very strong wind blowing down into the wheelhouse. This is generated by the slot, the gap between foresail and mainsail and its hitting the wheelhouse bulkhead behind you to slow the boat down. Shut the lid when sailing.

5. Instrumentation.  I use the wind instrument extensively and believe it can show you early indications of wind change so that you can take almost pre-emptive action. I also use the plotter SOG and boat log readouts together to determine instantaneous tidal flow fore or against the current course. The LM27 with it's long keel is very susceptable to adverse tidal conditions.

6.  Feathering propellor.  I know this is a very expensive piece of kit but I have one and I believe it's worth at least an extra knot to the LM27 and makes going about very much more slicker, sometimes you can be on the next board without loosing more than a knot- subject to sea conditions of course.

7. A good set of sails. Mine are now 18 years old and will be replaced in the next few years. The main is now a very odd shape when you look up on the leaward side.

I also believe that the after part of the genoa is the most important bit of sail on the boat and you need a large genoa so that this bit is truely fore and aft not at an acute angle

8. Mainsail track. I never found that the original 60cm mainsail track has any effect on sailing. My boat never seems to respond to mainsail twist at all or or kicker tension come to that, not that you can do very much with that short a track but when close hauled the sheeting point is too far inboard to induce the right sail shape so I have fitted a much longer track right across the after deck. When close hauled you can at least sheet the main down vertically to get a decent shape. Does any body else have the same experience with sail twist and lack of effect?

Finally,  I have found that the LM27's nemesis is a certain short sharp sea state which induces that pronounced  hobby horse action and you're not sailing anywhere fast!   - I don't have a fix for this except to start the engine!

Hope this invokes some lively discussion - Happy laying-up to one and all.

Regards

Mick

[jandane]

What a nice, good, long one for this tiresome winter to come!
I will be happy to participate.......At first, we all have to be realise, that the theoretical top speed of a 27'er is 7,4 knots and this is due to the shape of the hull combined wi the length in water. (I have logged 9,6 knots on the GPS, but this was with the help of gravity. I was surfing down some rather long and tall waves with 17 m/s wind)
1. The bottom. It must be smooth like a baby's bottom. In Denmark, we have a lot of barnacles spreading their eggs and larvaes in the early spring. They stick and grow. We paint the hull every spring, with one of the anti barnacle paints available. Today, in Danish waters, we no longer are allowed to use the heavy stuff with a lot of poison, and the paints available today is, depending on the water temperature during the summer, not so efficient. As a result, I scrape the bottom once or twice a year. Put on mask, snorkel and swimming feet and equipped with a spatula (is this the word?) I dive and scrape off all the shells from hull, rudder and propeller.

2. Sail upright. In short: No. The speed of the hull through the water is affected by the length of the hull in water. The longer, the faster. Due to the shape of the hull, the total length of the hull's waterline becoms longer when heeling. This goes for normal boats up to around 10-20dg of heel. The optimum depends of the specific boat and for a LM27 it is around 15 degrees.This means if we can establish a heel of not more than 15 dg our maximun theoretical speed is highest. When heeling, the upwind part of the hull comes freee of the water, while lee side dips. Due to the hull shape, the total amount of square inches under water decreases (we lift more out of water than we dip in)and thus creates a smaller draft. To counteract this: The more upright the mast and sail, the more wind pressure on the sail and the higher speed. When heeling too much, the curvature of the lee hul under water will force the hull windward. This is due to the speed of the water along the lee hull increases and thus creates a lift towards lee, and the hull will start swinging into the wind. This must be compensated with the rudder and the more heel, the more rudder and the surface of the rudder ploughs through the water, creating a heavy draft. Further more, the hull free of water, facing into the wind, creates a bigger target for the wind and this, combined with a shorter keel in the water(due to the heeling) gives a higher drift. (this also explains why the two shorter keels on many British LMs are as efficient as those with one keel- when heeling, these boats have one straight keel in the water) Wind increases, the boat starts heeling more than 15-20dg and then we have to trim....on a half wind, we aim for 15 dg heel and a maximum rudder of 5 degrees. The best is if we can achive a almost neutral rudder. To gain this, we have to trim sails..........

3. Trim. (to be continued)

[nauticalnick]

Nice one Mick ! Something to concentrate the mind on rather than the up and coming expensive season.

1. Agree clean bottom is a must. l use the cheaper brands of anti-fouling and they seem to be quite effective in my sailing area. The weed growth is always around or just below the waterline on the sunny side of the hull when on her normal mooring so l occasionally use the deck brush to remove this growth sometimes from the dinghy to go further underneath the hull, the antifouling does eventually come off after 2 or 3 heavy scrubbing sessions.Where l moor we have particular type of worm which after a season or so leaves a very hard cast that even the most expensive anti-fouling cannot prevent, that's a pressure washer and scraper job to remove it.

2. From my sailing dinghy racing days the boat always went faster when sailed upright so that is something l have tried do with the bigger boats. With the LM30 l have found that handling and speed are OK up to about 15degs of heel above that the boat, as perfectly explained in Jandane's para 2, more rudder has to be applied to keep the boat on track therefore acting as a brake and slowing the boat down. Sail trim also plays a very important part in the heel/speed scenario.

3. My LM30 has a slight list to starboard when both the fuel and water tanks are full but have since found that battery box is not in the correct place. So when that is re-positioned (another winter job) and since putting the heavy locker items into the port side lockers l hope that an even keel will be restored. The initial list to starboard did not appear to effect the sailing performance.

More to follow .......

Nick.

[oceandancer]

Hi Jan,

Very interesting reply. From where did you get the figure of 25 degrees? Is is published anywhere? I have always thought of the LM27 shape as - well a bit on the tubby side without the long overhangs of a true racing yacht. The curve of the bow is really quite abrupt and the extension of waterline length therefore not very marked. I have always considered that the induced weather helm and corresponding rudder drag offsets any advantage gained by the slight in waterline length.

I appreciate the advantage of twin keels. Does anyone have any experience of sailing in a similar boats with and without twin keels and can advise on the difference?

Regards

Mick

[oceandancer]

Hi Jan,

Very interesting reply. From where did you get the figure of 25 degrees? Is is published anywhere for the LM27?
I do appreciate the theory but I have always thought of the LM27 shape as - well a bit on the tubby side without the long overhangs of a  racing yacht. The curve of the bow is really quite abrupt and the extension of waterline length therefore not very marked. I have always considered that the induced weather helm and corresponding rudder drag offsets any small  advantage gained by the slight increase in waterline length.

I also appreciate the advantage of twin keels. Does anyone have any experience of sailing in a similar boats with and without twin keels and can advise on the difference?

Regards

Mick

[pengwyn]

I agree all the above, clean hull, good trim and proper sails will contribute to increased speed (and fun) - but what would it mean in real life, struggling to get an extra fraction of a knot, even if the boat is already properly prepared and the optimal adjustements are made? That would remind me to some folks on the german autobahn. always trying to go at v-max and willing to spend extra money for 5% increase in topspeed. but you will meet most of them in the next traffic jam. wind of much less than 4-5 bft has the same effect on my LM, as traffic jam on the autobahn - average speed gets decreased to boredom. so to reduce time required for travelling one has to avoid traffic jam - and / or weak winds. if there is sufficient wind, I found the LM to be more than willing to go close to hull speed. one part of the skippers job seems to be, not to run into 'traffic jam' / 'no wind areas'. Proper planning and 'regarding the weater forecast as integral part of the rigg trim' might help to do so. Nevertheless, as I have to accept, not being able to change the weater - a 'plan b' is reuired for weak wind situations. Such an approach could be to increase the size of sails, as in many cases it's not 'no wind', it's just too little wind to keep the 'chubby LM' going at a reasonable speed. For the purpose of keeping my LM27 going, I use a 'blister' (like a genoa doped with anabolika, easier to handel than spi). At least that helps to push the speed from boring 0,5 or 2 knots (standard rigg) to 'almost reasonable' 2 to 3 (or more) knots (blister). But even booster rockets will not turn the LM into a 2000 hp speedboat, which is absolutely O.K. for me. But a lot (of sheets) seem to help a lot (to some extend and if reefing is fast, comfortable and safe, in case the wind changes its mind). Therefore I'm going to experiment with a 12m2 kite in 2017, to check if these colourful things kitesurfers use, might give also additional 'LM-thrust' when the wind is sometimes sleepy in summer. (kites need to be actively flown to generate a significant pull, so they might not be an option for single handed skippers (?). Also probably a smart storage bag is required, to get rid of the kite fast, when not in use). I'm not a racer, so this is 'just for fun and personal education' ;-) but hopefully might also reduce the need for additional engine hours during the baltic 'horse latitudes'in summer.
But after all... 'Life (& sailing) is a journey, not a destination'
and 'Getting there is half the fun' (sounds like already Confucius derived a lot of wisdom from sailing a LM ;-) )

Pen Gwyn

[jandane]

Hi Mick
Sorry...I have misread some of the danish trimming guides. For a boat type like ours, the best heel is around 15, and not 25 dg. It is a very general thump rule and I have not been able to find any calculations about this matter. Based on my own experience, the 15-20 dg is ok in a LM27 and not more.
Back to the layout and canopy etc...Yes, for sure if this was supposed to be a racer, many things should be cut off. I think we should look at the LM27 as it is, and within these parameters try to get the best speed out of the hull. I have been sailing a lot of sailboats with more sleek and slender layout and ofcause, they are much more vulnerable to mistakes. If we do all things correct with mast, heel, trim and so, in total we may get very little advantage, and as Pen writes: why should we?
I love to trim mast, rig, sails on my boat and when comparing to other LM27 I meet in Danish waters, I do go faster, but when meeting a LM30 I only see the rear.

[Charles]

Really interesting! I have never tried to squeeze the extra 0.1 of a knot out of the boat. I always try to trim my elderly sails as well as they will allow, but the most important thing for me is that the crew shall enjoy the voyage and not feel endlessly harassed to "pull that rope, no not that rope, that b----- rope". We sail for pleasure and so the more upright the boat the better, and at less than 2 knots SOG the motor goes on. Mind you, when I am on my own it is a different matter, but then it is me who is pulling the ropes with Olaf the autopilot on the tiller, and though he is pretty good going to windward, he is not that sharp going downwind so occasionally we have words!

Keep the ideas coming all of you.

Charles

[jandane]

For sure you are right, Charles. Also for me in normal sailing, I do not sail for NM but for hours, and really do not care how fast it goes. I just found the opening of this thread amusing and as a way to spend a part of the winter.
Now:
3. Trim.....In my opinion, 3 things are for trimming. A) the mast. B) The sails and C) The hull with weight and balance.

[oceandancer]

Hi All,

Whilst on the subject, how do you brace yourself when heeled? The LM27 cockpit is very wide for a sailing boat and I am quite short! so I can only brace against the opposite locker when seated right aft next to the tiller. I have installed kicking straps which I adjust for my height which help a bit (see pic) . Mind you being short does have it's advantages when getting into some of the tight spaces and I do have full standing headroom in the cockpit lockers!





Regards

Mick

 

[jandane]

What a ferry you have, Mick. I am 1,84 meter and weight 108 kilos, so my LM 27 is never causing problems in that direction. I just sit.

[Charles]

Mick

The previous owner of Marguerite dealt with this by installing two strips of hardwood along the length of the cockpit sole, each about 6" from the centre line, which gives you something to brace your feet against when the boat starts to heel. I think it is visible in a photograph somewhere on this web site, but I can't remember where.

Charles

[oceandancer]

Hi Charles,

Yes I have often thought about doing this. Does it get it the way? have you ever tripped over it?

Regards

Mick

[Charles]

No Mick. The cross section of each baton is only about 15-20 mm and they are rounded on the corners.

Charles

[nauticalnick]

The fitting of a cockpit foot brace is quite common in the modern yacht, even though the helmsman may be, on most yachts, braced behind the wheel the rest of the crew do need something to stop them ending up in a heap on leeward cockpit sole or worse still !

Trim, l think is quite important, gaining the extra 0.1 + is very satisfying and can play quite a lot in crew moral if things are not looking too good.Whilst it has no significant effect on the passage time it makes me feel good !! Also you get to know what setting is best for the boat and the prevailing conditions. Sails set correctly for the prevailing conditions reduces heel and therefore less pressure on the helm ( also keeps the crew happy ). Mind you l'm not into tweaking the backstay etc every two minutes more a case of adjusting the halyard tension, mainsail out haul and mainsheet. My LM30 doesn't have a mainsheet track the sheet is fixed to the eye on the cockpit roof. This may be changed in the future.

The headsail is usually set unfurled and l only furl as last resort as l have found that once you start to furl they loose their shape, l've also found with the '30' that the genoa sheet car plays a bigger role in sail shape then on previous boats. l'll be acquiring a replacement genoa this winter so we'll see how that performs in the spring.

Nick.