Multihull Weight Saving Stratagies

[sailorcherry]

Did you do some speed tests and weight tests before the transom conversion? That data would be cool to know.

Yes, I agree, inexpensive if you are experienced or say in a cruising destination with inexpensive skilled labor (like Mexico).

Absolutely my point - dump a bunch of batteries and load up on solar on the arch. It's so affordable now and cats have the real estate - so why not?

If you had an arch or davits wide enough to carry all your solar needs there would you do semi-flexible? I thought they weren't as efficient? Or has that been worked out by now?

Originally Posted by thinwater

Absolutely. I added 2' to the transom of my PDQ; really cleans up the wake. A large number of cats cold benefit from this simple surgery. Also a nice swim/loading platform and a smoother ride. All positives.

Expensive if you are not a dab hand with FRP. Not too bad if you are experienced.

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Semi-flexible vs. rigid solar panels. I had rigid panels on the hard top for ~ 8 years before I sold the boat.

[mikedefieslife]

Originally Posted by sailorcherry

You must have a heavy cat then, right? Something not very performance oriented I take it?

Pretty heavy for its size yes, though still only around 3.5t (kg) It's an old Prout Snowgoose 35 with solid GRP throughout, narrow beam and low bridgedeck. It's at the complete opposite end of the performance scale.

[smj]

Originally Posted by sailorcherry

How about adding some to lose some, by adding transom extensions?

We all know some owners added them and some builders also, ex. Seawind 1000 - 1000XL.

It seems added capacity aft sure would be nice for affording an arch to hold lotsa solar in the best charging location and lose weight by removing batteries and full water tanks for a watermaker. Or do it to make up for the added payload aft for a bigger/faster dinghy and water toys.

Not to mention the handling improvements (pitching and a little more speed), ideal swimming, dinghy and boarding platform.

It's a mod I've had planned for a long while for whenever I became a cat owner. It just seems like a good add-on at a low cost via diy or by a yard vs the builder reaping the benefits with selling you a 2'-4' longer cat.

Any before and after data would be really appreciated from owners who have done so already.

We added 4’ to the sterns of our Seawind 1000. Greatly improved the motion, added some speed and cleaned up the wake. Best modification we have done to any cat.

[Nicholson58]

Originally Posted by Training Wheels

So, is that a Nicholson 58 multihull? All I can say is “no, not the rum!”.

Big old school mono

[valhalla360]

I know the anti-propane crowd will scream bloody murder but a propane/electric fridge is a option on a cat (yes, you have to install it properly). A single BBQ propane tank will feed it for a few weeks and will weigh far less than the batteries & solar array to feed a standard 12v fridge.

The fridge is often the main driver for a larger battery bank/solar array.

[swanpol]

best for weight saving,,
cruise solo, leave your wife at home¡¡¡¡
dry boat , no beers or alcool,,

[Nicholson58]

Originally Posted by sailorcherry

Did you do some speed tests and weight tests before the transom conversion? That data would be cool to know.

Yes, I agree, inexpensive if you are experienced or say in a cruising destination with inexpensive skilled labor (like Mexico).

Absolutely my point - dump a bunch of batteries and load up on solar on the arch. It's so affordable now and cats have the real estate - so why not?

If you had an arch or davits wide enough to carry all your solar needs there would you do semi-flexible? I thought they weren't as efficient? Or has that been worked out by now?

like Trinidad. Great labor rates in Chaguaramas, Trinidad at Power Boat or Peaks. We leave our boat there during hurricane season.

[Nicholson58]

Originally Posted by swanpol

best for weight saving,,
cruise solo, leave your wife at home¡¡¡¡
dry boat , no beers or alcool,,

Just think of the weight savings in shoes alone.

[thinwater]

Originally Posted by sailorcherry

Did you do some speed tests and weight tests before the transom conversion? That data would be cool to know.

Yes, I agree, inexpensive if you are experienced or say in a cruising destination with inexpensive skilled labor (like Mexico).

Absolutely my point - dump a bunch of batteries and load up on solar on the arch. It's so affordable now and cats have the real estate - so why not?

If you had an arch or davits wide enough to carry all your solar needs there would you do semi-flexible? I thought they weren't as efficient? Or has that been worked out by now?

Just a few tenths of a knot motoring at knots. a little more if going to weather at higher speeds, since all the weight is on one hull. That's all theory suggests. Greater improvement has been reported for overweight boats. Also subtle improvements in pithing and handling. The real improvement is boarding dinghies and kayaks. The extensions took me about 30 hours of labor spread out across a week.

Most cats probably have enough space on the hard top without a arch or crowding the davits. I like keeping the davits clean and I dislike arches; windage is just as bad as weight. Rigid panels are fine so long as you can mount them flat and DON'T add an arch, which defeats the "reduce weight and windage" point of all this.

But this is not strictly a cruising cat thread. For example, I added a 50W semi-flexible panel to this F-24. A rigid panel would work, but this was a non-trafic area and this panel is lighter and presents no windage. There is no reason not to use a mix of types.





The efficiency of semi-flexible panels is the basically the same as rigid panels because they use the same cells. The cells are only semi-flexible in the sense that thin glass is flexible, and if you flex them repeatedly they break, so careful, well-supported mounting is vital. They are the same cells, without the glass and frame to protect them. The people you see flexing them in videos are idiots. True flexible panels, on the other hand, are more flexible and MUCH less efficient and not very durable. I would never suggest them for a boat.

[sailorcherry]

Originally Posted by smj

We added 4’ to the sterns of our Seawind 1000. Greatly improved the motion, added some speed and cleaned up the wake. Best modification we have done to any cat.

Nice! Did you do any rudder mods due to the extensions? How was balance?
Have any before and after data, for speed, capacity etc? It seems motion is vastly improved, but the potential payload improvements really have me interested... you know being a woman for all my shoes. [emoji12]

[thinwater]

Originally Posted by sailorcherry

Nice! Did you do any rudder mods due to the extensions? How was balance?
Have any before and after data, for speed, capacity etc? It seems motion is vastly improved, but the potential payload improvements really have me interested... you know being a woman for all my shoes. [emoji12]

Speaking only for the PDQ, so long as the extension is not too long, the rudders generally work the same. A little more speed and cleaning up the wake makes them more responsive, off-setting any effect of the extra length. Backing seemed smoother because the transoms were more streamlined.


Power boats seem to be different; extensions can really change the steering.



But don't add more weight! We're kicking you off the thread!


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As a funny aside on shoes, I may have more than my wife, but different:
https://sail-delmarva.blogspot.com/2...any-shoes.html

[sailorcherry]

Haa! I promise not adding, just swapping....and not for shoes but for rigid water toys.

Funny you mention it, nice breakdown on your blog there because I absolutely believe, have seen that, boat hoarding is not gender specific...but sometimes we women get blamed for it [emoji34] Thanks for revealing the truth.....Mr. Bootman...uh huh ha

Originally Posted by thinwater

But don't add more weight! We're kicking you off the thread!


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As a funny aside on shoes, I may have more than my wife, but different:
https://sail-delmarva.blogspot.com/2...any-shoes.html

[Chotu]

Originally Posted by valhalla360

I know the anti-propane crowd will scream bloody murder but a propane/electric fridge is a option on a cat (yes, you have to install it properly). A single BBQ propane tank will feed it for a few weeks and will weigh far less than the batteries & solar array to feed a standard 12v fridge.

The fridge is often the main driver for a larger battery bank/solar array.

This is true. I have a wonderful propane refrigerator and freezer the size of a small house unit. They are front opening (no more taking everything out to get to the thing at the bottom) and incredibly efficient. The propane use Valhalla mentions above is spot on. That's exactly how much it uses. A couple BBQ tanks and you're good for a month and a half, minimum. I make ice for drinks and keep ice cream in it. Freezes meat at ice cream temperatures so it lasts indefinitely.

Best of all? No thru hulls or salt water pumps to replace. All air cooled.

[Training Wheels]

I’m on a diet; I figure I could lose 20 pounds!

[mikedefieslife]

Originally Posted by Training Wheels

I’m on a diet; I figure I could lose 20 pounds!

If it's anything like motorcycling though rider weight doesn't come into play much as it is used as ballast.