Extending a Lagoon 40

[Simi 60]

Originally Posted by smj

The original Seawind 1000 stern extensions were just that, sticking a stern extension on an existing boat.

Exactly
And they became better for it.
I have done several step jobs on cats over the years, every one of them improved performance, useability and resale value.

Originally Posted by Sailing August

Naval Architect & Marine Engineer weighing in here.
Such a modification would easily cost > $100k. In my opinion it is not worth the effort and cost. The custom modification will also decrease the value of your production catamaran. Save the $100k and apply it to the purchase of a different catamaran.
Catamarans are selling very quickly. Im sure your production 40' Lagoon will not stay on the market for very long. Take the sale proceeds and the additional >$100k you were going to spend and buy a newer, bigger and more optimized design. Just my humble opinion. Good luck and please keep us posted.

It could easily cost that if you were a clueless dolt who had a penchant for being ripped off.

Originally Posted by Cheechako

This has got to be the worst case of 3 foot-itis I've ever heard of.... really?
$100k will not be enough to do this.

Rubbish
Could do it 6 times over for that price easily if doing it yourself

[Cadence]

Originally Posted by Simi 60

Exactly
And they became better for it.
I have done several step jobs on cats over the years, every one of them improved performance, useability and resale value.



It could easily cost that if you were a clueless dolt who had a penchant for being ripped off.



Rubbish
Could do it 6 times over for that price easily if doing it yourself

Selling the boat and buying a longer one might be cheaper?

[Simi 60]

Originally Posted by Cadence

Selling the boat and buying a longer one might be cheaper?

If you think you can sell the boat
Pay brokerage fees
and buy a bigger one for $20k difference.

[Dsanduril]

Originally Posted by Paul Howard

I extended the stepped hull transoms on my Manta catamaran by two feet (Eric Lerouge design) and she sailed much better for it.
The boat used to squat and the bottom step was underwater. I made a mold in place by screwing some battens and arborite to the hulls, extending the upward curve of the underwater hull shape, waxed it up and laid up some solid glass, then added some interior framing with foam, fiberglass and epoxy panels, added a top (floor) part that extended across the top of the lower step to the new hull transoms and had about a 36" long boarding step. I faired in the outboard side so the profile was now further sloped rather than rounded and left the inboard side low for boarding from the side. I removed nothing, never cut into the existing part of the boat, so the extension could be torn off and the watertight integrity of the hulls was still intact.
We sailed that boat about 60,000nm, heavily loaded and she leveled out nicely, as lots of the storage space and tankage for water and fuel was under the cockpit and aft lockers, dinghy in davits, etc.
We had about 500kg of sealions resting on them in Argentina and Uruguay and never a problem. I sold the boat about 5years ago, she is still sailing with those extensions.
The only problem was that the rudders were not moved back and the longer extensions would hit the dock if not careful when pulling away.

This It's not that hard a task, and for catamarans with the engines installed well aft the extra buoyancy (even if small) added to the stern can have considerable effect on boat motion. Adding to the list of production cats, this is essentially what was done to turn the Outremer 50 into the 55 Light (yes, in the production run there were other differences, but the big change was adding five feet to the back end of the hulls without increasing accommodation space, etc.).

There was another thread on this topic not too far back with other reports from satisfied customers.

[radamspse]

This L 420 had extensions to both stern and Bow

https://au.yachtworld.com/boats/2007...n-420-3733603/

The owner thought it improved both performance and comfort.

To my eyes the stern mods are ok but the bow extension looks hideous

Bob

[Sand crab]

I think the OP already dismissed the idea of adding the 3' in the middle of the cat in his original post. So let's not talk about the $100,000 job any longer. The simple fact is hull extensions work. Almost all the cats are heavy in the rear so the improved buoyancy is great and add the extra waterline and now you have a win-win situation. Except for the price. If you're handy and do your research it's not that difficult for a DIY job. It wouldn't be that much in materials, epoxy or other resin, glass, foam or balsa or maybe strip planked and some incidentals. The haul out and yard fees would be the big costs.
BTW I saw a strip planked bow extension so it can be done.

[Uncle Bob]

Originally Posted by radamspse

This L 420 had extensions to both stern and Bow

https://au.yachtworld.com/boats/2007...n-420-3733603/

The owner thought it improved both performance and comfort.

To my eyes the stern mods are ok but the bow extension looks hideous

Bob

I think you are being overly generous with your praise.

[Simi 60]

Originally Posted by radamspse

This L 420 had extensions to both stern and Bow

https://au.yachtworld.com/boats/2007...n-420-3733603/

The owner thought it improved both performance and comfort.

To my eyes the stern mods are ok but the bow extension looks hideous

Bob

I can taste quite a bit of sick in my mouth
That's a Barry Crocker.

[Factor]

To say hideous would be kind, are we sure its real, looks like someone has gone silly with MS paint

[JasonS]

A couple of Manta 38/40s have extended the aft steps to “become 42s”. They were done in Guatamala and my understanding is that the molds are still at the yard. The owners were pleased with their improvement, which reduced the large second step down, made dinghy boarding easier, and added some additional buoyancy. However, this doesn’t make them the same as a Manta 42 as saildrive and rudder placement are not the same. My understanding is the change did make at least one boat harder to sell. We love our Manta 40. If we decide bigger is better, we will look to upgrade to something 50+, where avg speeds and reduction in hobbyhorse motion may be significantly different.

[downunder]

As well as Seawind 1000 stern extensions quite a few Seawind 1160's have had successful stern extensions.

2 years ago I had 700 mm (2ft 3.7 inches) added to my Voyager 1040 powercat.

Cost commercially around A $30,000. Results all positive no downsides.

The stern extension mirrored the underwater shape of the Voyager 1100 done by the builder.

[CATJAVA]

I’ve seen about 8 cats undergo added “sugar scoops” from 2-4ft. All the owners liked the improvement in speed and flotation. Cost was all under $5000 usd, but were done at either Monty’s in Qld. or in the Philippines. It’s an easy, cheap fix that’s done more often than you think. It’s not rocket science, so I don’t know where some of these opinions come from; must be a lot of armchair sailors on this forum...

I know that s/v Soggy Paws did one when they added a heavy fridge in the cat they had just bought which put the stern too low in the water. They always do good documentation on their blog so check it out!

Evan on cat JAVA (which is a Crowther Design 85 from a 46ft mold which was stretched to 48ft by added sugar scoops)

[Paul L]

Lagonda 440 Impi getting a stern extension
https://www.instagram.com/p/CKPtERer...=1kao6d3f4cwx5

[spiv]

A lot of people don't know what they are talking about.
I read the first few replies and got fed up.

I've done it on my 380 bows, covid stopped me from extending the transoms, but I will do it soon.


Just with the bows extension, boat goes faster, points better and pitches less.


Didn't cut the boat, didn't get extra internal space, just buoyancy.

Doing the transoms will improve more than the bows, it's a known fact to those that understand hydrodynamics and cats.

Where are you?
I could give an excellent contact in Tunisia, he assisted me, but he alone could carry out the extensions now that he got the know-how.

I don't have time to help, but if you were to make me an offer that I cannot refuse, I could write down an "how-to" and give you lots of pics.

[jimbunyard]

Would say 'typical catamaraners', but will instead say, 'free crabs tomorrow...', and wish you all long and storm-free lives...