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Nacra 450


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Greetings from Athens, Greece.

I am a new nacra 450 owner, i bought it used a month ago and i have started sailing it. I have allready 10 hours on it. My first question/problem i have with the boat is this : When i have the wind in front of the boat ( i dont know yet the words in english, hope you can understand me) and the boat goes in one hull the other hull that moves on the water tends to dig the water. Unfortunately three days ago i had an accident after the hull went down below the surface (deeper than it must get i assume) and in a blink the cat loosed its speed and the mast went on the water. I did get the cat on both its hulls again and when i started again the boat did the same thing again with the hull in the water. When i turn around 180 degrees (the wind was in front of the cat again) i saw that the other hull didnt have the same tendencie to dig into the water. Please advice me what is going on. Is there a matter of setup or the cat some kind of problem? Thank you in advance.

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When the hull begins to go down move towards the back of the boat. Don't wait until the boat starts to loose speed. This will bring the front of the boat up. The idea is to keep the boat even.

As you are just starting out my advise is to sit further back from the start. When you feel more confident move further forward to level the boat.

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Welcome to the forum.

I sail a NACRA 4.5 which is equivalent to the 450.

I'm not sure why your cat tended to nosedive on one side only. Were there any waves or was the water flat? You are more likely to nosedive if you sail into the waves.

Make sure you sit towards the bak of the catamaran. If it starts to nosedive, let the jib sheet out a few inches.


[This message has been edited by CleverNickname (edited 01 August 2007).]

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Both of you are absolutely right. The fact is that the day i was sailing the cat, there were enough waves on the beach, the wind was at around 4-6 bofor and on the one way which i had the pitchpoling i was going with the wind on the front of the cat. When i was turned around i had the wind on my back, which i havent the pitchpoling effect. So, i assume that you are right and on the other hand it seems logical that the weight of the boat regarding the onboard people has something to do with it. If i have the same effect in the future how can get out of it?? By releasing the rope of the main or by playing with the rudders? Thank you all for your interest.

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Do not attempt to save the boat with the rudders. They will act as breaks and make the matter worse.

Keep the rudder action very smooth at all times.

The aim is to keep the bow of the boat half way down into the water.

So as the boat starts to did the bow you move weight back and out from the boat.

Once you are as far back and as far out as you can be start to Alter the dip of the bow with the main or jib sheet by letting the power off the boat a little.

Also you want to turn down from the wnd not up into it when the boat is dipping.

I think the difference you found with the two hulls will have been about what angle to the wind you were.

Sail fast.

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You have also been told to stay back on the boat to keep yourself safe as a newbie. This will keep the sterns in the water which is slow. Always be aware of your sterns, not just your bows. The quieter you can make your sterns the better and this is usually achieved by getting them out of the water.

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  • 1 month later...

Greetings from Athens. The summer is over, we are all back to work, but we still sailing, the weather is still warm enough to do so. I have 2 questions. The first is about the problem i had with the cat about the one hull that was pitch poling. I maybe found out what is the problem. I had the boat in the water for 10 days and i didn't think of get the water out from the back ( you know the 2 valves on the back of each hull, I dont know the exact words, hope you understand). So when i got the cat on the trailer i open the two valves and the hull that has the pitchpoling had a lot of water, i mean the one hull must have about 2 liters of water and the other, the one with the pitchpoling, must have about 20 liters. So i figured out that maybe thats an issue about the pirchpoling. I have to mention that despite your opinions above i had the pitchpoling effect twice a day where i was sailing for ten days. How can i fix the leak?

The second question is, what clothing i need so i can sail at winter?

Thank you in advance.

Manolis Anthis,

Athens, Greece.

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First thing to check would be the washers on the bungs (valves) at the rear of each hull. If these have perished, or a not sealing properly, the hulls will take on water.

I'd recommend that you remove both bungs assemblies and replace and reseal them. Also make sure your hatch covers in the top of the hulls are sealed properly.

If that doesn't solve your problem, then I'd be very closely inspecting the hulls for a crack somewhere.



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You do not want a lot of water in the boat...anytime.

Worst result is much more pressure on the frame and mast.

Put boat on trailer.

sight carefully along keels for wear.

Run hose into the hull and check keels again.

Lean boat back with water in it and check bungs.

If there is damage you will ahve to take mast down.

When you do, invert boat and use hose again to chach chain plates, inpsection ports and beams.

A good silicon sealant tube and gun, pot rivit gun and hacksaw are basic requirements for a plastic and ali boat.

Keels need epoxy or similar. I use epoxy. For keels I use a pure epoxy undercoat and when it is still going off I place a coat of epoxy with half glue and half filler powders.

If you are doing this, mask the boat..15ml either side of keel is plenty.

If you do this with the boat inverted in the sun you can do three coats of epoxy a day and not have to sand between coats.

Sand a good keel coat smooth and then final coat of pure epoxy, sand, undercoat and top.

If you beach the boat you should make the keels extra thick with a sacrificial amount the sand can wear down.

Really though you should get a nice little anchor and have a padded anchor bag made that either clips onto tramp or goes in a pocket.

Anchor off shore on islands so you don't have to drag the boat.

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Well, i have inspected the hulls all the way around and there is not any issue of them being damaged in any way. The keels are a little bit scratched because it is true that i drag the boat each time i finish sailing. Though the damage from dragging them on the sand is not an issue. About the two hutch covers, the previous owner of the cat has replace the one of them and the one that has been replaced don't have screws instead of the one that is older. He has put it permanently on the hull with some aliminium nails ( i don't know how you tell those in english, i can show you some pics if you think that i must do so).

The bungs don't loose any water because i have allready check this.

Warbird when you say "Run hose" you mean i put a hose and fill wth water the hull inside?

My thoughts on the issue are that maybe i have leaks from the screws that holds the aluminium tubes in front and back from the trampoline with the hulls. Also the screws that holds the base of the rudders on the back and generally any screw thats on the cat.

The question is how can i inspect those screws, just unscrew them and put some silicone and then again screw them back in?

Also im thinking of doing a repaint on the boat. I dont have a paint gun (airgun) but i can find one for 2-3 days. I dont have any experience on painting with airgun, you think that is easy to do so? You see the cat is a little yellowish from the sun and i want to do a paint job to be new again. Also if i do so, where can i found the decals thats on each side of the hull (Nacra). Also i forgot to mention that the cat is not an 450 but a Nacra 4.5

Thank you for your interest.


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Hi Manos,

I use low air pressure around 1 - 2 lbs to test for leaks in my hulls, I never use water in the hulls. Never put more than 20 litres in the hull especially if it's sitting on the trailer.

I would try to restore the hulls rather than paint. Use Gamatone (phosphoric acid) to clean the yellow stains, leave on for 10 minutes and hose off, apply a 2nd coat if there is any remaining yellow stain.

Wet and dry your boat finishing with 1200 grit paper than apply some restorer wax followed by a liquid wax, I'm using 3M polishes. You should be pleased with the results.

If you decide to repaint the boat find someone who knows what there doing with a spray gun.

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Graceland is right about the amount of water. 5 litres odd is all that is needed.

I can always find ALL leaks with this method and am very happy with it.

Grace is also right about trying to stave off painting the boat.

!200 the whole boat.

Use a marine gel coat cutting restoring and polishing compound.

Always do the least to your boat before you know a little more.

Re winter clothing.

I use 3ml wetsuit longjohns. Rash shirt, spray jacket. Add a polyprop T shirt underneath if it gets cold.

You might want to buy a drysuit but I like being wet.

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By the way, I have often completly sealed my boats...it is VERY important if you do this to fril holes in the insection caps. About 4ml and then you can tie a knot in the end of some 3ml and thread it through and lash the lid onto one of the bolts inside the port. Boat can't split in the heat and you won't lose a cap over the side.

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BTW again. You may think you are not creating a problem dragging the boat on sand but you most certainly are!

You will create a big keel job and you will find out you need one by filling a hull with water.....You might get to bend your mast badly and only just get home in 30 knots like I did when I was a newbie.

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Thank you for your replies.

I will do the things you said about the leak. Another thing i mentioned is : Do i have to disassemble the entire cat, meaning the tramboline and the aliminium tubes that holds it and the mast, and look at the screws that holds the aliminium tubes on the hulls? Do i have to put some silicone on the holes that the screws bolt on the hulls? Besides the leak on the one hull, i want to inspect the whole cat for whatever restoration it may want. For example i change the ball where the mast locks when you put it up. It wasnt in a bad condition but i changed it just in case. I also changed all the ropes, did some oiling on all the moving parts, wheels etc.

In general please advice me, besides the leak problem, how can i take care the cat so i can live with it as long as it can get.

Also, does anyone knows where can i find the Nacra self stickers that the cat has on its hulls side? Im asking because i want to change them, they are in a bad condition.

Thank you very much for your time and interest. Waiting anyone of you next summer here in Greece so we can go for a ride with the cat and have a good time with all the rest.

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No, you do not have to pull the boat apart unless the leak you identify is in this area and cannot be repaired without taking this action.

First identify leaks. Mark then with a dot from a felt pen so you will not forget where they are.

Then quielt create a plan and go through the actions carefylly and thoughtfully. Realise that as you do this work you become more connected to your boat and will ultimately sail better because of the extra understanding you create.

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  • 2 weeks later...


I did a very stupid thing today!!!

As i was inspecting the hulls i unscrew the three screws that holds the base of the chainplate on the hull. I cannot screw them back again!!!!

Is there any rusks from the inside????

I dont have access in the inside of the hull!!

Please tell me what i have done?

Is it reversable??

What must I do now to fix this stupidity??

Please help me out...

Thank you.

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