modifications

[kgi]

I want to add three feet to the stern of my boat, rudder and running gear unaffected, i "think" i have it sorted on how i want to do it, but different brains operate on different planes so comments ,ideas, what not to do, etc would be welcome........keith

 

[ccscott49]

Maybe a silly question, but what for, asthetics, or to add a platform for stowage of gas bottles gear etc, as I've seen on some longdistance liveaboard types?

 

[kgi]

No its a catamaran and it squats like a bitch under power (far more than mono's do). none of the backstays etc will be affected, yes iknow i'm supposed to sail everywhere but when i need to use the engines its abysmal.

 

[Mr Cassandra]

Hi . Why don`t you stick it on the bow ,at least you will be able to see where your money gone .cheers bob t

Bob T

 

[peterk]

Any other type of boat
I'd have said forget it.

But two friends of mine succsessfully lengthened their multis
one a 43 ft cat by 4 feet,
the other a 25 ft tri by 3 feet.
Both boats originally had nearly vertical transoms.

Both guys added what's called a sugarscoop
with a racy backwards-downward angle on the
sterns
- the tri only on the mainhull.
the cat built in three steps
under which he henceforth stowed his fenders on one side
and ABC snorkel gear on the other.

Both boats - with no naval architects involved
though I'd still run it by one... -
gained speed

...peter, www.juprowa.com/kikttel

 

[chippie]

As catamarans are usually very narrow at the stern(s) it would probably pay toget some calculations done to make sure you are going to achieve what you want, as it is width that is probably needed.

Good luck

 

[oldsaltoz]

G’day Keith,
You need to do some calculations to ensure you get the lift required. In most cases (on Cats), this will mean not just extending the transom, but also extending the underwater section from the rudderpost back and perhaps trimming a little off the top of the rudders to accommodate the changed line. You may also like to consider extending the line to finish above the water line by around 150 mm to provide extra buoyancy when under motor and a clean exit (less wake) when under sail.
I have extended two cats this way with very good results, more speed, a lot less noise, and improved handling. Good luck with your project and please let us all know how the mod’s turned out.

Andavagoodweekend Old Salt Oz……

 

[oldsaltoz]

G’day Keith,
You need to do some calculations to ensure you get the lift required. In most cases (on Cats), this will mean not just extending the transom, but also extending the underwater section from the rudderpost back and perhaps trimming a little off the top of the rudders to accommodate the changed line. You may also like to consider extending the line to finish above the water line by around 150 mm to provide extra buoyancy when under motor and a clean exit (less wake) when under sail.
Also consider using epoxy resins as they provide a better bond and the end product will be lighter and stronger, also make sure the fibreglass fabric is the correct type, no chopped strand, aim for one part resin to one part cloth, wax resins are closer to three to one resin / cloth.
I have extended two cats this way with very good results, more speed, a lot less noise, and improved handling. Good luck with your project and please let us all know how the mod’s turned out.
I hope this helps.

Andavagoodweekend Old Salt Oz……