Beaching Catamarans

[JustMurph]

A stow-away dingo could be interesting.

You can also beach if you have beefy rudders, like my mates crowther 226A. No issues resting on them.

[catsketcher]

Pescotts also sit on their rudders okay. It just means you usually have shorter rudders than a cassette boat. It means you probably get less rudder area (because they are shorter) but far less complexity.

[GRIT]

Originally Posted by catsketcher

I have normal rudders and normal looking cassettes. There is just a 5mm taper in the cassette sides - tapering inwards at the bottom and tapering 5 mm inwards at the front. As soon as the cassette slides back a bit she has some play but she is absolutely tight when in place.

I don't think parallel sided cassette sides are as good an idea as a slight taper. This fits well with making the cassettes moulded from the slot (IMHO). My first cassettes made joggly noises at night so I made new ones that were moulded from the slots with the un-noticeable taper I built into the boat. Been silent and working well for 2 decades now.

Cheers

Phil

Thanks for that description Phil.

So your rudders are kickups, and when fully deployed, they "jam" into the cassette just enough to stop the rattling.

Have I got that right? That's a good plan, and I will see what I can do there. We do have play at the rudder/sheath interface as well, which I planned to take care of with some sunbrella, at least temporarily.

But we also have play in the pins. I suspect the machining grooves in the delrin have worn smooth, or some such. Either way, they've got to be changed too.

Would you have a photo to share? I'm having a bit of a problem picturing your setup. It sounds like it might not be just the rudder pivoting. Do you have a housing pivoting with the rudder, into a tapered slot in the hulls?

Our rudders pivot into a sheath of sorts. The sheath is hinged to the boat. It sounds like your rudders may have shafts, and sit in a pivoting housing.

Thank you.

Cheers.
Paul.

[GRIT]

Matt. This is very close to what we are looking at doing.

https://image.jimcdn.com/app/cms/ima...8138/image.jpg

https://www.graingerdesigns.net/trimarans/

[Matt Johnson]

Originally Posted by catsketcher

Pescotts also sit on their rudders okay. It just means you usually have shorter rudders than a cassette boat. It means you probably get less rudder area (because they are shorter) but far less complexity.

Yup. We're able to keep high aspect ratio with a 2 m depth and small chord of the rudders, but with a 540mm draft by going this route. More work/expense than fixed rudders, but I think it will be worth the effort.

[Matt Johnson]

Thanks GRIT. I think I now understand what you're describing. Instead of the delrin insert taking the load, you're instead planning to use roller bearings as the gudgeon. Have you talked to Jefa about this? They may have something usable right in their catalog.

Here is the first round of test designs for our boat's set-up. If we were to change to a bearing instead of the delrin bushing, I'd need to open the well a bit more to accommodate the additional diameter, but we might-as-well do it right now while I still have the patience/equipment to get it done.

[GRIT]

Your rudders protrude 2m into the water? Wow. That ought to grip the water well.

I'll be interested to see them when you're done.

Ours are 1.8, long, but 60 cm of that is in the sheath, and 1.2 is in the water.

That's a nice looking system. Is it Aluminum? I had planned on building in Carbon, as they are now,
but aluminum would be nice too. And much faster to build.

Cheers.
Paul.

[Matt Johnson]

Originally Posted by GRIT

Your rudders protrude 2m into the water? Wow. That ought to grip the water well.

I'll be interested to see them when you're done.

Ours are 1.8, long, but 60 cm of that is in the sheath, and 1.2 is in the water.

That's a nice looking system. Is it Aluminum? I had planned on building in Carbon, as they are now,
but aluminum would be nice too. And much faster to build.

Cheers.
Paul.

I looked up the plans up again... it's actually 1.765 depth for the rudders. We decided not to build the rudders ourselves. The Vietnam yard has the molds already and the thin foil shape makes any variance off plan noticeable in performance.

The system in the photos is all stainless for quick build and testing (this is the production test boat). We're either going to be aluminum or carbon with the finished product. We are building our cassettes.

Matt

[GRIT]

Those rudders are still very deep. That'll work well, especially at higher speeds, or surfing, when the water gets a little "airy".

We've been happy with our rudders, but I'd like to lighten the load on the autopilot a little by installing the hinges on the sides. In the mean time, I'm tinkering with the idea of a small forward extension at the top of the rudder, that'll just miss the hulls. I don't think I'll catch lines with it, as the skeg deflects them most of the time, and when they're not deflected down, they hit about 60 cm from the waterline.

Cheers, and thanks for your input.

Paul.

[malbert73]

Originally Posted by GRIT

Thanks SMJ.



That's kind of you to say. We're very happy with her; and as we finish the interior, and add our own personal touches, we enjoy her even more. She's exactly what we'd hoped she'd be.



Cheers.

Paul.

How long did it take for you to build her- nice cat!

[Chotu]

Originally Posted by fxykty

You don’t have to have kick up or cassette rudders to be able to ground your boat as long as you have robust skegs (with a foot plate to prevent sinking into the sand/mid). Although we do sit bow down as our skegs are 1.1m and the deepest point of the hulls 0.8m.

Attachment 255174

Works well nose in to a beach with a slope, but the one time we dried out on a sand flat (Indian Head) it wasn’t that comfortable to sleep. And all the Australian critters that can come on board!

Oh good lord!!!

What critters were able to board the boat while you tried to sleep??

Not good!

I’ve only been boarded (at anchor) by a big iguana so far. He turned the color of my topsides which was strange to see. While at the construction dock here, I’ve been boarded by bugs of all types and a rodent.

Kind of wish I saw this type of discussion before I built my boat. I built according to plan. Standard flat side kick up cassettes. They definitely rattle around.

[GRIT]

Originally Posted by malbert73

How long did it take for you to build her- nice cat!

Hi, malbert73.

Thank you for the compliment. We always appreciate hearing that; it's been a long journey.

We started the build in 2010, and are still at it. We launched in the fall of 2019, and installed the mast and sails in the spring of 2020.

It's mostly cosmetics now, but of course, that's the thing that shows the most!

The interior of the hulls still need paint, and panel edges finished. The pilot house needs drawer faces, and the cabin sole is just paint at the moment.

Thanks for your interest.

Cheers.
Paul.

[catsketcher]

Originally Posted by Chotu

Oh good lord!!!

What critters were able to board the boat while you tried to sleep??

Not good!

I’ve only been boarded (at anchor) by a big iguana so far. He turned the color of my topsides which was strange to see. While at the construction dock here, I’ve been boarded by bugs of all types and a rodent.

Kind of wish I saw this type of discussion before I built my boat. I built according to plan. Standard flat side kick up cassettes. They definitely rattle around.

Gday Chotu

Yeah I had rattly ones too before I moulded them off the slots. There is millimetres in it. If I was you I would just do the same with some honey wax release agent and some glue filler. Get someone else (because it is epoxy) to put a small dab of epoxy around the bottom of the slot. Wax up the cassette first. Then drop it in and squeeze out the excess. Then when cured you should have a little wedge all around the bottom of the slot. Repeat on top but this time put the little TOP wedge on the cassette itself. Then a little lift gets the cassette all nice and loose again. It shouldn't be hard to make the little wedges top and bottom if you mould them in situ.

cheers

Phil

[CaptainRivet]

Originally Posted by catty

Great advice. Attach sacrificial shoes to keel base. ie hardwood or whatever. Certainly wouldn't recommend beaching too centreboard boat owners. Be careful in suburbia, some locals may take offence and call the EPA if it looks like your about to anti-foul. The ability to take the bottom without fear of damage certainly multiplies the number of available anchorages ten fold.

Hi catty,

Could you show me your sacrificial shoes on the keel base please.
Or anyone else, how would something like this shoes look like?
I have a FP Lavezzi and massively reinforced the whole hull, keels and all bulkheads(+ added several new bulkheads) during the repairs caused by a 8m rogue wave. Aim was to reinforce structure which is 300% better then a new one now and to be able to beach it safely even if conditions are not that good.
Still on the dry dock for 1 month and could add the keel shoes if I know how they should look like.
Looking forward for more tips how to beach or fall dry a cat.
Stern Anker and face outwards is a very good tip:thumb
More tips like this please from sailor who do that regularly.

[Sos]

Originally Posted by CaptainRivet

Hi catty,

Could you show me your sacrificial shoes on the keel base please.
Or anyone else, how would something like this shoes look like?
I have a FP Lavezzi and massively reinforced the whole hull, keels and all bulkheads(+ added several new bulkheads) during the repairs caused by a 8m rogue wave. Aim was to reinforce structure which is 300% better then a new one now and to be able to beach it safely even if conditions are not that good.
Still on the dry dock for 1 month and could add the keel shoes if I know how they should look like.
Looking forward for more tips how to beach or fall dry a cat.
Stern Anker and face outwards is a very good tip:thumb
More tips like this please from sailor who do that regularly.

Here are some pictures of a repair I had to do to our keel and replacement of our timber keel shoe -