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Had anyone here sailed one of those?

At a claimed cruising weigh of slightly above 8 tons, relatively slender hulls, and with daggerboard they seem to be capable of equal or better performance than eg Catanas or others in the semi-performance range. 

The aluminium construction is certainly rather unique for a series built catamaran. I was just about to accept a balsa core sandwich as a compromise for my next boat, but aluminum? :-) 

Paul 

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I've seen discussion of this on the other forum, CF, in years past, there is small "Google Custom Search" box in the middle of the drop down when you click the search button.  It can be an exceptionally helpful feature, (Take note forum admins).  Best search function ever, in my limited tech experience/capacity. 

The boat is from down under and there are a lot of those guys on the Farrier group, they seem helpful.  If you can decipher the logo on Rasp's pic, maybe that is a lead.  Especially if its a charter and you can go try it out.

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  • 1 year later...

Congratulations. 

I bought something different in the meantime, so my interest in Mumbys is only academic at this time...

However pictures of pretty boats are always appreciated. :)

Paul

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  • 10 months later...

Toolbar: Thank you. I totally missed this. I'll chuck a few photos below. :)

Soma: Unfortunately, I believe the Philippines yard has been shut down and not sure if it'll be back. Tim is still selling the plans, for anyone that would like to build one elsewhere. You could float out of the yard for a bit less than Jamie says in the vid above but I'll be a pretty basic build. Most will end up spending a good chunk more after launch to really bring them up to spec and finish them a bit better.....but that's no different to most boats. And still a cracking good deal. And the resale value is crazy high.

EarthBM: The central helm was only seen on the very early 48s like Mozart (currently for sale). Most of them, like Jupiter 2 and mine have a stbd side saloon bulk head mounted helm. In my opinion it's pretty good. You can sit in the seat and have full shelter from the sun and the elements, or stand on the step there and have sight lines to all four corners of the boat, which makes manoeuvring in tight confines really easy.

My example would have been seen in Jamie's video above nearing the end of the build when his was starting. It's had a bit of a rough life and is a work in progress. Definitely not a pretty as Jupiter 2, which I think is one of the nicest looking examples. That said, she's been an awesome boat. Fast, safe, very comfortable. It typically cruises up around 10 knots, with my top so far being 17.

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The vid about building; really facinated to see advanced boats like this is buildt on a shore and in a shed with basic tools (if you call mig-welding basic....) - for use here in the cold I think they get some things to solve - cold bridges etc. but good in the ice. 

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They seem be pretty good in that respect with a few exceptions. I know of two of them that had some cracking around the prodder bobstay tangs, but not others. I found out that my boat in its earlier days had a crack around of the the little skegs/braces for the prop shaft in one hull. I haven't heard any issues with any of them other than that. As it turns out, the previous owner of my boat "found" a few reefs with the bottom of this boat.....and aside from a few sections that aren't quite perfectly straight, it's fine. It really is a testament to the strength and durability of the design.

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Sort of surprising that the French, with all their success with alloy monohulls and love of multihulls did not take this route.

Eric Taberly's Pen Duick 3, 4 and 5 were alloy and each ground breaking.

What is the plating thickness and alloy grade jmurph and love the name Twocan with her bare alloy topsides.

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1 hour ago, Keith said:

....Banana 43 .... and one is even yellow - spend 300K EUR on a big banana.... the jokes in the bars around the world... 

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Boardhead: They're 5083, 4mm hulls and 3mm most other places. All of the materials and parts for these boats are shipped from Australia to the Philippines, to ensure the quality. I quite like the raw aluminium look too. :)

EarthBM: There are water tight compartments fore and aft in each hull. In addition to that there's about 5t worth of positive buoyancy in the foam between the outer aluminium skin and the inner fibreglass skin.

Keith: Mowgli, the Banana 43 is a local boat to me. She's been out of the water for a while now I think. 

 

 

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4 hours ago, soma said:

Man, I like the new Jupiter video. That’s a great boat for the money (seemingly). 

Now I’m dreaming of building an aluminum custom cat!

Totally agree - you're not the only one!

Any idea how fast the Mumby 48 is, like is it Outremer 5x fast?

I've been looking for some ratings/race results but can't seem to find anything. 

Where would it likely land on this list?

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4 hours ago, gspot said:

Any idea how fast the Mumby 48 is, like is it Outremer 5x fast?

I've been looking for some ratings/race results but can't seem to find anything. 

Where would it likely land on this list?

Couldn’t find any data off any ratings website, so data used is from designer/selling agent info, which is suspect at the best of times. So, fag packet, FWIW:

Mumby 48      LOA: 14.50m, Displ (lightship) 8500kg, SA (upwind) 116m2, Base Speed: 11.9 knots.

Outremer 5X  LOA: 17.98m, Displ (lightship) 14800kg, SA (upwind) 199m2, Base Speed: 13.8 knots.

Base speed is average speed. Top speed (without screechers/kites) is double Base Speed. Top speed upwind is approx Base Speed.

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4 hours ago, Sidecar said:

Couldn’t find any data off any ratings website, so data used is from designer/selling agent info, which is suspect at the best of times. So, fag packet, FWIW:

Mumby 48      LOA: 14.50m, Displ (lightship) 8500kg, SA (upwind) 116m2, Base Speed: 11.9 knots.

Outremer 5X  LOA: 17.98m, Displ (lightship) 14800kg, SA (upwind) 199m2, Base Speed: 13.8 knots.

Base speed is average speed. Top speed (without screechers/kites) is double Base Speed. Top speed upwind is approx Base Speed.

This is neat! What's the formula? Does it take LWL/hull beam into account, or is it kind of contained in the Displ and LOA?

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47 minutes ago, EarthBM said:

This is neat! What's the formula? Does it take LWL/hull beam into account, or is it kind of contained in the Displ and LOA?

Base Speed only takes LWL (effective), Displ and SA into account. Different versions of it lie (or used to) at the heart of OMR, MOCRA and Texel rating systems. Mine is an “old” version, current at the time I was designing my boat. Current version (BSpd) can be found here:

http://www.multihulldynamics.com/news_article.asp?articleID=34

When using the formula, make sure you are comparing like for like, especially in terms of Displ and SA. If you are using rating data, some systems include a crew weight allowance (eg MOCRA and Texel) and others (eg OMR) don’t, but are regatta specific for declared minimum weights. Best to get data off of just one rating spreadsheet if you can. Texel does take Beam into account, and calculates catamarans to be slower than tris for the same data. It can also give an indication of stability.

if you register on the site, you might even be able to get a direct comparison between the Mumby 48 and whatever you are interested in.......

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gspot: Definitely not 5X fast. These things are a fast cruiser and not a race boat. I don't know of any of them that are seriously raced.

There is good potential there. Tim's own boats are usually kept pretty simply and are sail away at under 6.5T. Put a big rig on one and some bigger boards and I'm sure you could extract some impressive performance. The standard rig is fairly conservative, both in sail area, sail construction and the size of the spars. The standard boards aren't that long (1.2m past the hull).

My numbers certainly aren't as fast as sidecars calc, but my boat is loaded up full time liveaboard cruiser that probably sits closers to 9 or 10t and has working sails that are pretty average. Upwind we'll usually sit on 8.5 knots, everywhere else around 10. Max of 17 surfing so far. Other boats have seen low 20s. I do sail it a bit more conservatively than the previous owner..

EarthBM: 12.07

 

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1 hour ago, jmurph said:

My numbers certainly aren't as fast as sidecars calc, but my boat is loaded up full time liveaboard cruiser that probably sits closers to 9 or 10t and has working sails that are pretty average. Upwind we'll usually sit on 8.5 knots, everywhere else around 10. Max of 17 surfing so far. Other boats have seen low 20s. I do sail it a bit more conservatively than the previous owner..

Numbers provided were approximate theoretical maximum speeds in flat water. 

At 10 tonnes Displ, the Base (or average) Speed drops to 11.3 knots.

Upwind, waves will knock a fair bit of speed off, especially on smaller lighter boats.

 

 

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1 hour ago, jmurph said:

gspot: Definitely not 5X fast. These things are a fast cruiser and not a race boat. I don't know of any of them that are seriously raced.

There is good potential there. Tim's own boats are usually kept pretty simply and are sail away at under 6.5T. Put a big rig on one and some bigger boards and I'm sure you could extract some impressive performance. The standard rig is fairly conservative, both in sail area, sail construction and the size of the spars. The standard boards aren't that long (1.2m past the hull).

My numbers certainly aren't as fast as sidecars calc, but my boat is loaded up full time liveaboard cruiser that probably sits closers to 9 or 10t and has working sails that are pretty average. Upwind we'll usually sit on 8.5 knots, everywhere else around 10. Max of 17 surfing so far. Other boats have seen low 20s. I do sail it a bit more conservatively than the previous owner..

 

Thanks for the testimonial!

I think those are pretty good numbers for a loaded boat, average sails, a conservative sailing style and a non-rotating mast (based on photos of other Mumby 48s).

With some fresh laminate sails and a good crew that can push the boat you might well end up with @Sidecar's numbers. 

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2 hours ago, gspot said:

Thanks for the testimonial!

I think those are pretty good numbers for a loaded boat, average sails, a conservative sailing style and a non-rotating mast (based on photos of other Mumby 48s).

With some fresh laminate sails and a good crew that can push the boat you might well end up with @Sidecar's numbers. 

Base Speed can’t see and doesn’t allow for any “imperfections” in rig, sails, hulls, foils or crew. Even antifouling (as opposed to dry sailing) will knock off half a knot.

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14 hours ago, Sidecar said:

At 10 tonnes Displ, the Base (or average) Speed drops to 11.3 knots.

 

 

That sounds about right. Today we watched the start of the Brisbane to Gladstone race, then sailed over to Moreton Island along side the pack. 25 knots true, 2nd reef in, 80º TWA and we averaged about 11.5 knots (generally 10.5 - 12.5) with a top of 15.5 in a 30 knot gust.

Amusingly,  for a while there we were sailing along side the lead boats in the mono hull pack (aside from the super maxi Black Jack, which was long gone), on the same point of sail, trolling the fishing lines, eating a cheese platter and going about a knot faster. :D

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  • 2 weeks later...
  • 1 month later...
11 hours ago, toolbar said:

Try [email protected] And better ask for a Mumby. :-)

Paul

Sure, I'll design you a Murphy48. I can't guarantee it'll be any good though. :D

 

Mozart I think might have been sold now. I'd say it was priced a bit high for an older ex-charter example.

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  • 2 months later...

I'm sure some do, but most that I know of don't.

That said, despite living in a pretty warm part of the world I've never felt like I needed it. These boats stay surprisingly cool. In my judgement, a lot cooler than most fibreglass boats I've been on.

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In one of the Jupiter 2 videos he mentions he doesn't like to fill up the diesel tanks to save on weight. Are these boats really that sensitive to loading? With sailing performance being better closer to the empty weight than when actually in use/being lived aboard? It seems he doesn't have a ton of stuff on board and only the two of them so his comments are a little concerning.

 

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I think that's just performance catamaran owner weight anxiety, more than a real issue. :D

My boat sits a fair bit lower in the water since I bought it and moved aboard full time, with a fair few more toys than the previous owner, however I really haven't noticed any difference in speed. The difference is far less pronounced than the difference between between a dirty bottom and a clean bottom, which is very obvious. That said I'm still very conscious about the weight I've added and have been trying hard to keep it down.

A mate has just bought a Mumby that's structurally complete, but has no interior, so weighs in at 5t. It's sailing performance is off the charts. Much faster than mine (probably 9t) as you'd expect, on every point of sail. What seems to be the biggest difference is that the more heavily laden boat will need more power to climb over the ~10 knot hull speed hump, than the light boat.

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@jmurph

Thanks for that. I was hoping that's all it was. So if planning to be loading it up a bit more as a live aboard boat it could be compensated for with a larger sail plan? Also, as a live aboard how are you finding it? Anything you'd wished you'd tweaked if you'd had a hand in the build? How's the storage capacity for food, sailing gear, backup parts, etc (plenty, adequate, undersized & always juggling for space)?

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On 7/16/2021 at 3:14 PM, jmurph said:

That said, despite living in a pretty warm part of the world I've never felt like I needed it. These boats stay surprisingly cool. In my judgement, a lot cooler than most fibreglass boats I've been on.

This is a good point! With aluminum’s high heat conductivity (x5000 more than fiberglass) you have a natural heat sink all around you. 
 

The opposite logic in high latitudes of course…

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8 hours ago, bitbyter said:

@jmurph

Thanks for that. I was hoping that's all it was. So if planning to be loading it up a bit more as a live aboard boat it could be compensated for with a larger sail plan? Also, as a live aboard how are you finding it? Anything you'd wished you'd tweaked if you'd had a hand in the build? How's the storage capacity for food, sailing gear, backup parts, etc (plenty, adequate, undersized & always juggling for space)?

You wouldn’t need a larger sail plan on one of these, even loaded up. It’s a decent sized rig (18.5m mast, 76m main, 46m Genoa, 155m asym). Actually, the later model square top main is a little bigger.

As a live aboard it’s an excellent boat. There’s a heap of space for tools and spares along with a huge dedicated work bench. The galley is huge, open, light and airy and very well connected to the rest of the boat. I use few of the lockers in the adjacent cabin as overflow pantry space. Lots of room for sails and sailing gear. There are plenty of detail things I’d change in a new build, like adding more hanging space, or having square corners on the settee (rather than rounded off) but the bones of it are all good! Happy to expand on them for anyone seriously looking at a build.
 

3 hours ago, EarthBM said:

This is a good point! With aluminum’s high heat conductivity (x5000 more than fiberglass) you have a natural heat sink all around you. 
 

The opposite logic in high latitudes of course…

You have 40mm of foam between the inner and outer skins everywhere above the water line, so that does a nice job of insulating heat and sound.

It is a little chilly in winter, but I suppose any boat will be when you don’t have a lot of thermal mass around you.

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3 hours ago, jmurph said:

Happy to expand on them for anyone seriously looking at a build.

Yes, please. Currently working on a timeline and depending on finances I'm hoping to potentially submit a build request in about 5 years if he's still building them then.

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  • 1 month later...

Hi Folks,

I have read as many posts and Mumby build threads as I have found over the last 10 years or so, and I believe Tim (and others) still cut out all panels by hand (ie. skillsaw, plasma, etc) and are not CNC cut.   I understand this may make sense with the remote building he does..  I have dreamed about building a Mumby since then... 

I would be interested in knowing if Tim would ever sell plans and CNC cut files (for single builds) using approved suppliers/ cutters that will not cheat him out of revenue by reselling files, etc.

I am  in Canada, and having built a 25 ft aluminum power boat a few years ago, and doing all of the cutting by hand, the thought of paying a premium to have a large shipment of precut panels arrive so one can start tacking panels together is very appealing....  I spent many weeks building a jig for upside down building and then watched videos of guys who were tacking together hulls from Specmar.com the day they arrived..   Being so large, I don't doubt that you may still require some sort of jig, but it would still be awesome to have frames and panels precut and precise..

When I bought my bulk aluminum sheets a few years ago (20ft x 6ft) I paid about $3Cdn a pound.. if I had bought a design which had CNC cut flies,  there was a metal supplier/ cutter in New Hampshire (about a 10 hour drive away) who would have sold me the cut aluminum for about the same price (factoring in the exchange rate).  I went with my plans as I wanted an inboard diesel and it was very hard to find plans, with CNC cut files, which did not have anI outboard.  In hindsight, I should have used a design with  cut files, bought an outboard and been in the water a year or two earlier... although  I am happy with my boat now that I am using it..

On another note, I have seen build pics of some Mumbys where the two hulls were built separate and then aligned and joined together, and at least one where the frames were configured so both hulls (jigs) were align and connected before any skin went on.  I would be interested in knowing some of the learnings which have came out of the two methods.

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  • 5 weeks later...
On 9/10/2021 at 10:38 AM, Northeaster said:

Hi Folks,

I have read as many posts and Mumby build threads as I have found over the last 10 years or so, and I believe Tim (and others) still cut out all panels by hand (ie. skillsaw, plasma, etc) and are not CNC cut.   I understand this may make sense with the remote building he does..  I have dreamed about building a Mumby since then... 

I would be interested in knowing if Tim would ever sell plans and CNC cut files (for single builds) using approved suppliers/ cutters that will not cheat him out of revenue by reselling files, etc.

I am  in Canada, and having built a 25 ft aluminum power boat a few years ago, and doing all of the cutting by hand, the thought of paying a premium to have a large shipment of precut panels arrive so one can start tacking panels together is very appealing....  I spent many weeks building a jig for upside down building and then watched videos of guys who were tacking together hulls from Specmar.com the day they arrived..   Being so large, I don't doubt that you may still require some sort of jig, but it would still be awesome to have frames and panels precut and precise..

When I bought my bulk aluminum sheets a few years ago (20ft x 6ft) I paid about $3Cdn a pound.. if I had bought a design which had CNC cut flies,  there was a metal supplier/ cutter in New Hampshire (about a 10 hour drive away) who would have sold me the cut aluminum for about the same price (factoring in the exchange rate).  I went with my plans as I wanted an inboard diesel and it was very hard to find plans, with CNC cut files, which did not have anI outboard.  In hindsight, I should have used a design with  cut files, bought an outboard and been in the water a year or two earlier... although  I am happy with my boat now that I am using it..

On another note, I have seen build pics of some Mumbys where the two hulls were built separate and then aligned and joined together, and at least one where the frames were configured so both hulls (jigs) were align and connected before any skin went on.  I would be interested in knowing some of the learnings which have came out of the two methods.

I have been in contact with Tim Mumby and he does have some CNC cutting file's when you purchase the plans from him. I'll be getting what ever I can CNC cut before i build.

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21 minutes ago, Mid life change said:

before i build.

Please, please, please post your construction efforts here.  I think many of us would wish to experience this adventure with you.  Besides, think of all the free, professional advice... <_<

If you pull the trigger, may I be the first to congratulate you!

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  • 6 months later...

Thanks for all the advice and info.

One of Jupiters videos shows a lot of condensation inside the cabin from the alu roof supprts.  Is this a big issue with the Mumby?

What would be the fastest time to have one made at the Mumby yard in your experience?  Are they backed up for years?

Cheers!

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 I do get similar condensation on colder nights, but it's not a big problem in my opinion.

As far as I know the wait for a build is a good 2 or more years now, though there are a few other builders around who are looking at building them.

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