Meat Wad

Grainger R42 - 12.8mts Performance Cruiser Trimaran

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It's a cool boat, nice to see some new Grainger trimaran designs progressing to build, Jamie Morris will inject some artistry into the build I often look at pictures of Cutloose and admire his work there, gorgeous boat and I'm sure this will be no different.  From a personal perspective I would have liked to have had an aft cabin on a boat this size but I get that many people would prefer the extra cockpit space. 

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Jason on board Spirit visited Boatworks and saw this recently. I had a messenger chat with him briefly. It was on the same trip he saw Bullfrog and posted his video on that.

I know he posts on here, perhaps he might have some comments/pics?

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We managed to talk with Jamie Morris the builder of Venom and made a little video.  If your interested in seeing some more of her please follow the link  R42 Venom

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On 1/6/2019 at 7:00 AM, trispirit said:

We managed to talk with Jamie Morris the builder of Venom and made a little video.  If your interested in seeing some more of her please follow the link  R42 Venom

https://www.youtube.com/watch?v=Ry6O_WnP6kc

at 6:04:

Quote

It should fly a hull [the main hull] in about twelve knots true.

 

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Great, and well worth watching.....:)

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Fabulous boat, great video, Thanks.

44 kg aft beam - that’s 97 pounds? Amazing!

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2 hours ago, boardhead said:

Fabulous boat, great video, Thanks.

44 kg aft beam - that’s 97 pounds? Amazing!

Looked extremely beefy to me, 56 layers of uni carbon in the top cap. That is stout! But yes, pretty light for that size beam!

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The aft beam on my 40’ tri with 16 layers top, 14 layers bottom, continuous from ama bottom to ama bottom, 36’ long bands, 8” wide over a solid 6 and 3 1/2 pound density foam core came out around 270 pounds using uni glass, including the fairings.

I thought that was light, the whole boat goes sailing at 5,600 pounds.

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4 hours ago, boardhead said:

The aft beam on my 40’ tri with 16 layers top, 14 layers bottom, continuous from ama bottom to ama bottom, 36’ long bands, 8” wide over a solid 6 and 3 1/2 pound density foam core came out around 270 pounds using uni glass, including the fairings.

I thought that was light, the whole boat goes sailing at 5,600 pounds.

Is your forward beam chopped to allow passage through the bulkhead? I know it's common, but I like seeing a bulkhead on either side of a beam, even if partial a bulkhead. I have no idea how the forward beams are tied into this boat, so I shouldn't be commenting. It seems like a cool boat and the structure was well shown in the video. Be nice to shoot the next video during lunch break or whatever they call that in Australia.

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No, both beams are continuous, my wife and everybody else, has to duck under but I would not compromise the filament continuity.

The front beam ties in with the daggerboard case  and the curved to match bulkhead beneath, you can see how it goes together on the video Wess posted about my boat.

If you are interested quiz me there so we are not stomping on somebody else’s subject.

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Oh Boy!

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4 hours ago, woodruffkey said:

Ha thats Funny.

9.6 meter BOA gives a beam section weight of 4.5 kg per meter for a 42 ft boat. 

The shrouds are attached to the floats .

I call BULLSHIT even if made out of unobtainium.

The Carbon flange off cut they hold up to the beam lets us do a quick rough calc on the weight of the flanges alone

scaling  off using the guys hand,and I'm seeing 70 kg just there.

Were only being fed half the story here.

 

Doesn't anyone remember Graingers last efforts with a tri this size.

The floats fell off. Twice. Lets see whats been learned

Bwahahah

 

Scaling off of a human hand is not the most accurate wieght estimator. Perhaps a certified scale would be better. I don’t think people like to go on video making false claims that can be easily verified. Jamie seems to have been working on this for a while and I can’t imagine he’s that far off from his weights using vacuum infusion. I could see it being heavier if they weren’t bagging every part. 

Apparently we shall see what the lessons learned from their mistakes are soon.

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My weight estimate for the uni carbon in that beam using high modulus carbon and aerospace composite techniques (vacuum bagging with quality resin) is 37kg, so I don't think he is lying, plus I agree with Sail4beer, to what end?

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Just picking up the beam and setting it in position, even if it was not actually weighed, would confirm or refute Jamie’s statement and really no reason to make some crazy low weight claim, to what end?

The workmanship and commitment to create a boat that raises the bar is to be commended, long time since Bullfrog was built.

I am amazed that a beam of those dimensions and strength requirement can be built to that weight but never having designed or built in that material I stand to be amazed.

The mast on my boat is Hi Modulus Carbon, 58’ 6” long, monolithic, dry braided, resin infused, compacted and cured in an autoclave by Composite Engineering, The structural design and engineering was by Ted Van Dusen, MIT, owner of Composite.

I designed and built the boat and gave Ted the rig layout, support locations and a weight that generates 120,000 ft. lbs. of righting moment.

Ted tells me the rig represents the lightest he ever built for the task in hand, I can’t break it. It weighs 243 lbs and dressed with all the standing rigging and halyards two guy’s can carry it. Not many Hi Modulus rotating carbon wing spars being made outside France Ted tells me.

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21 hours ago, Russell Brown said:

Is your forward beam chopped to allow passage through the bulkhead? I know it's common, but I like seeing a bulkhead on either side of a beam, even if partial a bulkhead. I have no idea how the forward beams are tied into this boat, so I shouldn't be commenting. It seems like a cool boat and the structure was well shown in the video. Be nice to shoot the next video during lunch break or whatever they call that in Australia.

As seen here: https://www.graingerdesigns.net/photo-galleries/r42-build-gallery/

The forward beam on this Grainger R42 trimaran is actually a pair of beams attached to a bulkhead, with space between them for a passage through the bulkhead.  Looking at the video again more closely, at 7:50 he is saying that each one of these two forward beams weighs 44 kg., or 88 kg. total (194 lbs.) for the pair.  He doesn't mention the weight of the rear beam, which is a single unbroken piece from ama to ama.

Forward beams:

fwd_beam2.jpg.8e2b35fcb7d0b383db351868953be3de.jpg fwd_beam4.jpg.d977bf5460114f5574e2dc79630aeda6.jpg

fwd_beam3.thumb.jpg.1d32e2223cb5d34075b9fbb7b782ea72.jpg

Single rear beam:

rear_beam.thumb.jpg.79880e28b8929fd9ad890d5aa998e8cd.jpg

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You are right ProaSailor, my  mistake, each refers to port and starboard not front and rear, makes sense.

Thanks for pointing out my misinterpretation.

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Board head was talking about his own boat Skateaway, which is 40’ x33’ and weighs 5,600 lbs including the carbon mast.

Your not doing too well on reading, watching simple videos  and interpreting what you read and see into useful information. 

 

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13 hours ago, woodruffkey said:

When I learn a thing or two about life I willl Feel free to appaologise to you Boardhead

 

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And thank you for the 21 downvotes today Woodruff. 

 

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Interesting forward beam connection, most new designs have big ring beams in there to take the loadings.

 

IMG_1222.JPG

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4 hours ago, Waynemarlow said:

Interesting forward beam connection

Yeah, I'm not saying it's not going to work, the bulkhead looks beefy enough but it doesn't look like an efficient load path connecting it to the beams...
There might still be some more pieces to go in mind you as it doesn't look like it's been laminated to the bulkhead.

It would make more sense if the bulkhead was extending outside of the hull to increase the length of the overlap (there's going to be a fairing on there anyway). They may still add some other "partial" bulkhead on the forward face of the beam and/or some braces perpendicular to the bulkhead picking up the end face of the beam.

It's not like I've done the calculations or anything so what do I know! It looks like a cool boat for sure.

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Update on build progress/launch?

 

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This cruiser racer Grainger Trimaran is getting very close to finishing. Go to Venom Sailing page for all the details! Cheers all.

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Where? The FB post? All I saw was this

5EC96B92-D315-4302-9318-44617866AFD6.jpeg

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Look here and scroll down

Deck-on-from-above-215x215.jpg

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Looks like a weapon.  Needs to have the boards in the floats like the Rapido 40.  Makes the layout much better on a cruising tri.

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Boards in the floats add cost, complexity, weight, load up the beams, imbalance the boat and you still gotta put a structure under the mast to stop it spearing down thru the deck.

Lifting boards in the floats together with a daggerboard in the main hull works great on big boats - over 50' min - but no way in an all round performance 40 footer - maybe for a reachamaran but then there's the proa option.

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I would still think that lifting foils and t-foil rudders would help at this size, no? Not much added weight (already have stiff carbon beams) and they can be fully retracted in the case of the c-boards. At least in my experience they make smaller boats act much longer, its like adding 10-20% more bow volume with less drag penalty and upwind you can really get the boat ripping with the ama/float in full skim mode...may not work at this displacement of course...

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     So C boards (the ones that fully retract) are all about lift, offering little resistance to leeway and at their best on a reach in flat water. The lift they generate does allow for lower volume amas with lower buoyancy wave piercing bows, if desired but that lift only occurs at speed and you can only “pierce” small waves and I mean small relative to the boat size.

     Small boats in flat water, OK but a 40’ trimaran ought to be venturing offshore, to justify it’s size and with that type of sailing other requirements become desirable.

    It might get windy and rough out there (read fun) and if you want to drive the boat hard in even moderate, let alone big or huge waves then you need a boat to take care of you, your crew and itself. To be fast and safe offshore this boat needs to be strong, light and possess good form stability.

    It’s now four or five decades ago that we learned the need for adequate ama buoyancy and in particular reserve bow lift to prevent or delay pitchpoling when reaching hard or wave induced rollover in serious shit.

    For fast boats “not much added weight” unless that weight brings a real benefit, is unacceptable.l

    Beams need to be strong, stiff is debatable.

    With C foils only in the amas your boat will go upwind like a square rigger offshore and in flat water upwind (90 degree tacking angle) does your boat do sixteen knots? Mine does. Long T foil rudders? I really need a rudder to get home so I like a really strong one in the wake on an even much stronger, impact absorbing , on centerline, daggerboard.

     All the above is applicable, in my experience, to 40’ or thereabouts sized, Offshore Trimarans.

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9 hours ago, samc99us said:

I would still think that lifting foils and t-foil rudders would help at this size, no? ... At least in my experience they make smaller boats act much longer...

Getting lift at the center/dagger makes sense, especially to skim the windward hull.

Question is, how much benefit do you get from JUST rudder t-foils and no center/dagger-boards? Seems like you'd still get SOME pitch-stabilization... but at what speeds?

Remember the Hobie bow 'foil' pitch pole preventers? How far we've come!

Randii

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19 hours ago, boardhead said:

     So C boards (the ones that fully retract) are all about lift, offering little resistance to leeway and at their best on a reach in flat water. The lift they generate does allow for lower volume amas with lower buoyancy wave piercing bows, if desired but that lift only occurs at speed and you can only “pierce” small waves and I mean small relative to the boat size.

     Small boats in flat water, OK but a 40’ trimaran ought to be venturing offshore, to justify it’s size and with that type of sailing other requirements become desirable.

    It might get windy and rough out there (read fun) and if you want to drive the boat hard in even moderate, let alone big or huge waves then you need a boat to take care of you, your crew and itself. To be fast and safe offshore this boat needs to be strong, light and possess good form stability.

    It’s now four or five decades ago that we learned the need for adequate ama buoyancy and in particular reserve bow lift to prevent or delay pitchpoling when reaching hard or wave induced rollover in serious shit.

    For fast boats “not much added weight” unless that weight brings a real benefit, is unacceptable.l

    Beams need to be strong, stiff is debatable.

    With C foils only in the amas your boat will go upwind like a square rigger offshore and in flat water upwind (90 degree tacking angle) does your boat do sixteen knots? Mine does. Long T foil rudders? I really need a rudder to get home so I like a really strong one in the wake on an even much stronger, impact absorbing , on centerline, daggerboard.

     All the above is applicable, in my experience, to 40’ or thereabouts sized, Offshore Trimarans.

I'm just going to run with "NO" to the above.

 

properly designed and built foils will be a benefit to a small tri, as for poorly done ones... thats another story and seems to be what you have experienced.

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On 5/16/2019 at 4:31 AM, boardhead said:

     So C boards (the ones that fully retract) are all about lift, offering little resistance to leeway and at their best on a reach in flat water. The lift they generate does allow for lower volume amas with lower buoyancy wave piercing bows, if desired but that lift only occurs at speed and you can only “pierce” small waves and I mean small relative to the boat size.

     Small boats in flat water, OK but a 40’ trimaran ought to be venturing offshore, to justify it’s size and with that type of sailing other requirements become desirable.

    It might get windy and rough out there (read fun) and if you want to drive the boat hard in even moderate, let alone big or huge waves then you need a boat to take care of you, your crew and itself. To be fast and safe offshore this boat needs to be strong, light and possess good form stability.

    It’s now four or five decades ago that we learned the need for adequate ama buoyancy and in particular reserve bow lift to prevent or delay pitchpoling when reaching hard or wave induced rollover in serious shit.

    For fast boats “not much added weight” unless that weight brings a real benefit, is unacceptable.l

    Beams need to be strong, stiff is debatable.

    With C foils only in the amas your boat will go upwind like a square rigger offshore and in flat water upwind (90 degree tacking angle) does your boat do sixteen knots? Mine does. Long T foil rudders? I really need a rudder to get home so I like a really strong one in the wake on an even much stronger, impact absorbing , on centerline, daggerboard.

     All the above is applicable, in my experience, to 40’ or thereabouts sized, Offshore Trimarans.

Interesting hearing your comments regarding a single daggerboard in the main hull Vs lifting C foils in the amas! Not sure what you sail or if you have sailed against a Rapido 60 upwind (17knts and tacking through a genuine 90 degrees, have plotter tracks to prove it ) but I can tell you it is by far the best performing big multihull to windward I have ever sailed , going faster and higher than any other boat in the fleet we have raced against .

 Sounds like I am agreeing with your points and with the Rapido 60 I am I guess!

So it was with some trepidation that I was convinced by Pete Melvin that it made sense to go with the foils in the amas Vs a single central board as on the 60 . What convinced me was his total confidence that the twin boards in the amas would be better upwind!

The foils are asymmetric and quite big. They give between 30 to 40% lift down wind and according to the designers and their VPP software will be better upwind than the Rapido 60 and it is great already! They will be very well built and structurally sound thanks to our open molded Autoclave cured process, and perfect in shape thanks to our new 7 axis CNC Robot machining center.

MM have tons of experience with boats with foils that go upwind like rockets so we are putting our money where their mouth is!  

Boat design is always a trade off between features so on balance we have a good way to hold the mast up as it sits on the fwd beam bulkhead , really nice saloon area because there is no daggerboard case screwing up the accommodation .

Yes it is all talk at this point till we get the Rapido 40 sailing but sometimes ya got to trust that your well qualified designer knows what he is doing, he hasn't let me down yet ! 

 

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Boardhead, sounds like an old school 40 tri vs a Rapido new skool grudge match. I'd love to see them take you on! I'll be making book and will have the odds shortly.

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Paul, I designed my boat in 1987 to the best of my knowledge/experience at that time. Check out the video Wess put up, everything there is true. I did have the good fortune to collaborate with Ted Van Dusen for a substantial improvement in the rig and also worked with some fine sailmakers. Jan Gougeon persuaded me to substantially upsize the rudder and the board and case were also modified. Skateaway will drive upwind at 16 in flat water whilst tracking through 90 degrees. I have sailed over the newer 12’s upwind - surprised me.

The main hull is extremely stiff fore and aft as a consequence of the unusual design and fiber orientation, it is also very light and strong, an excellent base for the rig.

My contention with multiple ama foils, as I stated is one of complexity, expense and weight on 40’ sized Trimarans and I have thought about it a lot - not sure macca did - who knows. I have to winch my board down - it diminishes the overall boat weight at over 10’ draft. I repeat that my interest is performance both offshore and inshore, the performance demonstrated in the video is in flat water with only 6’ draft and that does not work too well upwind in sizable waves.

I do not pretend to have anywhere near the experience and data base that Gino and Pete have amassed and I would really love to see more fast, fun offshore 40’ Trimarans around and available to the public.

If I still own Skateaway when the Rapido 40 splashes I would welcome comparing and offering any assistance I can.

Skateaway is light and simple, perhaps not acceptable to a market dying to have everything they see on a Mod 70 on their pocket rocket, I believe as Dick Newick started years ago, you can only have two out of the three.

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On 5/16/2019 at 11:16 PM, Rasputin22 said:

Boardhead, sounds like an old school 40 tri vs a Rapido new skool grudge match. I'd love to see them take you on! I'll be making book and will have the odds shortly.

Needs some numbers for those odds?

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"...he hasn't let me down yet" 

The problem with reputations is the folks doing the design aren't the same folks doing the build...so if performance doesn't match expectations you have all sorts of finger pointing away from themselves.   Now, if everyone has an equity stake in the project, that may be different.  

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Is it me or does the mast height look conservatively sized?

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Looks a little stubby, but it might be the camera angle...

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Lot of lens distortion in that picture - the stick is what - 60'?

Head sail on a furler and no runners - must be a very rigid platform.

When is the big splash and any numbers on sailing weight?

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On 5/15/2019 at 9:59 PM, randii said:

Question is, how much benefit do you get from JUST rudder t-foils and no center/dagger-boards? Seems like you'd still get SOME pitch-stabilization... but at what speeds?

Remember the Hobie bow 'foil' pitch pole preventers? How far we've come!

Randii

I have wondered this as well-- as my F31, with all its rocker, does pitch more than I would like in certain conditions.  Also would like to be able to trim the nose down a bit when sailing hard on the wind-- the faster we go, the more the stern sinks.   But when I think about how much the boat heels when pressed, I think that the tfoil rudder would be kicking the boat into the wind as you start to really haul ass up wind-- which you would have to then counter act with more rudder angle, which would be slow.

 

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The rig does a look a little small. For reference, a local Corsair 43 was refit early in life with an 80' rotating carbon rig for better performance in light air. The Corsair 37RS has a 51' rig. In both cases the boats are a good bit heavier than the Grainger, and often sailing in areas with less breeze than Venom. Still, it would appear the floats can support a slightly larger rig, potentially with rig canting an option for race mode :)

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On 10/4/2019 at 2:02 PM, Vincent DePillis said:

... my F31, with all its rocker,...- the faster we go, the more the stern sinks.   ...

 

Just curious, isn't it supposed to do that?  Supposedly the boat was designed to plane on that aft sugar scoop...not that I've ever seen any evidence that it actually works that way (no wake diminishing like you'd see in a true planing boat).   

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25 minutes ago, MultiThom said:

Just curious, isn't it supposed to do that?  Supposedly the boat was designed to plane on that aft sugar scoop...not that I've ever seen any evidence that it actually works that way (no wake diminishing like you'd see in a true planing boat).   

You don't think its planing so what do you think an F31 is doing sailing at 15-18 knots sustained which is something that boat easily and regularly does?

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3 minutes ago, Wess said:

You don't think its planing so what do you think an F31 is doing sailing at 15-18 knots sustained which is something that boat easily and regularly does?

I think the float is in displacement, and the main hull is being levered out of the water to some extent, and drug through the water really fast by a powerful rig.  Maybe planing to some extent, but doubt that is the main event.

I also think that the  aft biased rocker is there as much for safety downwind (suck the stern down to avoid pitchpoling), more than desire to promote planning.   Guessing  that generous  rocker is also a result of squeezing the necessary displacement into a trailerable length, while keeping the transom clear of the water at rest..

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27 minutes ago, Vincent DePillis said:

the  aft biased rocker is there as much for safety downwind (suck the stern down to avoid pitchpoling)

It's absolutely this, which incidentally makes the boat slower than it could be - but much more safe. It's all a compromise of course.

43 minutes ago, Wess said:

You don't think its planing so what do you think an F31 is doing sailing at 15-18 knots sustained

Unfortunately multihulls don't REALLY plane. The l:b ratio is simply too skinny. Of course, there ARE some tri's out there like ORMA's that do have a larger amount of their power coming from dynamic buoyancy ("planing"), but even these are not completely self supported and are still relatively in displacement form. Those ama's BTW look nothing like farriers, they are really flat instead of round with almost no rocker.

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To each his (or her) own.  And I ain't much for legalistic techno-lingo that don't align with what my eyes are seeing.  So I am going with "sweet" and "planing!"

 

 

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16 minutes ago, Wess said:

I ain't much for legalistic techno-lingo that don't align with what my eyes are seeing.  So I am going with "sweet" and "planing!"

 

Concur with sweet.  But what are your eyes seeing that is planing?  The wave pattern behind the boat never changes size....that's the most obvious difference between planing and not planing.  Anyone who has sailed next to a planing motorboat that slows down off their plane immediately sees the difference...virtually no wake and suddenly very big wake.  Multihulls go fast because they weigh very little and make small waves which they can drive over with the huge power available in the sailplan.  No need for hydrodynamic lift to go fast--to go faster you fit foils on them and then your wake goes away (ie, planing).

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7 hours ago, samc99us said:

The rig does a look a little small. For reference, a local Corsair 43 was refit early in life with an 80' rotating carbon rig for better performance in light air. The Corsair 37RS has a 51' rig. In both cases the boats are a good bit heavier than the Grainger, and often sailing in areas with less breeze than Venom. Still, it would appear the floats can support a slightly larger rig, potentially with rig canting an option for race mode :)

The rig is 64ft, the image is from an angle that does not do it justice.

Horsepower will not be an issue, the rig went up 1m during the early build process.

 

G42 Final Rig.jpg

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24 minutes ago, Lowgroove said:

The rig is 64ft, the image is from an angle that does not do it justice.

Horsepower will not be an issue, the rig went up 1m during the early build process.

 

G42 Final Rig.jpg

Interesting you say horsepower won't be an issue. At 1.4 x boat length it seems fairly conservative for a 10 metre wide tri compared to say  XL2's new rig at 1.6 x boat length. Standing by to see the power to weight ratio as XL2's is very high at 3.2 tons weight and 60 foot rig for a 38 footer. If Venom is 43 foot and 4 tons it could be considered underpowered by comparison. Greater waterline length and the trimaran factor will come into it. It may struggle against the likes of Rushour though.

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2 hours ago, square top said:

. Standing by to see the power to weight ratio as XL2's is very high at 3.2 tons weight and 60 foot rig for a 38 footer. If Venom is 43 foot and 4 tons it could be considered underpowered by comparison. 

Funny guy. 

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4 tons - long tons @ 2240? - that’s 8,960 pounds? - did the boat or components, during build, get weighed? How does the finished build weight look?

Interesting for me because the boat is very, very  similar to mine except the skins are carbon/epoxy vs glass/vinylester.

I was in fairly frequent discussion with Duane Zelinsky during the building of Zephyr, his Jim Antrim 40, another foam cored carbon/epoxy boat.

I was fortunate enough to sail Zephyr, double handed, on a couple of lengthy offshore delivery passages and get to compare her with Skateaway in a broad range of conditions, an invaluable experience.

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10 hours ago, Wess said:

You don't think its planing so what do you think an F31 is doing sailing at 15-18 knots sustained which is something that boat easily and regularly does?

    So as I understand it the magic number is 8:1 length/breadth - that’s the fineness ratio above which no displacement wave is generated.

    I think I am correct in saying this data was first confirmed in the development of destroyers a little over a hundred years ago.

    When designing a fast trimaran the ama will be that swift weight supporting shape, too slender to be stable by itself, the cross beams present it to the water surface as near upright as possible at maximum speed.

    A planing shape climbs out of the water and skims across the surface which requires a far greater power to weight ratio than a sail driven multihull can provide - not talking about ultra lightweight flat out racers here.

    The trick with a fast, single rudder/daggerboard trimaran is to arrange the weight/flotation/lifting surfaces such that the ama is presented to the water at an attitude where it presents the least resistance to foreword motion at the point of maximum righting moment - as the main hull becomes airborne- whilst maintaining full immersion of the foils to ensure control. 

    For shorthanded, offshore, trimarans the boat must take care of itself without the assistance of a significant amount of move able ballast in the form of a larger crew.

   That slender ama will slice through the waves with minimal resistance but it need not plane to go fast.

    

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24 minutes ago, SeaGul said:

A new boat that can compare to this is the Shuttleworth 39 Morpheus - its a little more race orietated - but still has touring capasities.  http://www.shuttleworthdesign.com/gallery.php?boat=shuttle39tri

Interesting that Shuttleworth with all his experience went for the one piece main beam.

Talks about the beam design around 4.30

 

 

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The Shuttle 39 is abit more race orientated - and then they prioritize the continious beam.

 

 

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If ya need a planing powerboat to catch me its planing.  How about this?  Planing?!

71343994_10216790260961276_368370669143982080_n.jpg

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13 hours ago, Lowgroove said:

The rig is 64ft, the image is from an angle that does not do it justice.

Horsepower will not be an issue, the rig went up 1m during the early build process.

 

G42 Final Rig.jpg

Look amazing.  She is going to be fast! 

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10 hours ago, boardhead said:

    So as I understand it the magic number is 8:1 length/breadth - that’s the fineness ratio above which no displacement wave is generated.

    I think I am correct in saying this data was first confirmed in the development of destroyers a little over a hundred years ago.

         

Erm...no

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so you're saying a hundred year old destroyer left no wake?  In my own meager experience all large power vessels leave huge wakes, warships being perhaps the worst.  I saw a recent vid where a newer warship intentionally used its immense wake to horribly disturb some practice "pirate" boats.

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It’s the bow wave that matters, not the wake.

 

it’s not at all about planing. It’s about the Froude number...

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1 hour ago, mundt said:

so you're saying a hundred year old destroyer left no wake?  In my own meager experience all large power vessels leave huge wakes, warships being perhaps the worst.  I saw a recent vid where a newer warship intentionally used its immense wake to horribly disturb some practice "pirate" boats.

No I am saying it did not generate a huge stern crest and mid length trough from which it could not escape - it's displacement speed max - destroyers don't plane but they do exceed displacement speeds - just like multihulls.

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1 hour ago, MultiThom said:

Erm...no

Did you check it out?

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1 hour ago, EarthBM said:

It’s the bow wave that matters, not the wake.

 

it’s not at all about planing. It’s about the Froude number...

Pray tell us more ---- Explain.

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1 hour ago, EarthBM said:

It’s the bow wave that matters, not the wake.

 

it’s not at all about planing. It’s about the Froude number...

https://www.boatinternational.com/yachts/yacht-design/the-owner-s-guide-to-superyacht-naval-architecture-part-1-learning-your-lines--723/page-2

Probably more than you want to know.

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30 minutes ago, MultiThom said:

Not really cos it did not explain why my boat does not hit a brick wall, speed wise at 8 knot and why there is no waterline length displacement wave at all and the immersed hull is not planing - maybe time to start a new topic if anybody wants to go further with this "mystery"

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22 hours ago, Wess said:

To each his (or her) own.  And I ain't much for legalistic techno-lingo that don't align with what my eyes are seeing.  So I am going with "sweet" and "planing!"

 

 

 

 

The hull is just really poor at making a proper bow wave.

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16 minutes ago, Dex Sawash said:

 

 

The hull is just really poor at making a proper bow wave.

It sure is - but why?

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I immediately regretted chiming in... Froude number just takes us back to hull speeds... as if it’s a one-dimensional problem. In fact the problem is at least two-dimensional — LWL/beam ratio clearly matters, although the speed x beam / LWL is pretty much always at subcritical levels. And then you start including chines and the conversation becomes just too complex. There is no closed-form solution so everyone’s opinions are equally worthless unless backed by empirical data.

On that, I’m very interested in the comparison of Skateway and Zephyr. 

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26 minutes ago, EarthBM said:

I immediately regretted chiming in... Froude number just takes us back to hull speeds... as if it’s a one-dimensional problem. In fact the problem is at least two-dimensional — LWL/beam ratio clearly matters, although the speed x beam / LWL is pretty much always at subcritical levels. And then you start including chines and the conversation becomes just too complex. There is no closed-form solution so everyone’s opinions are equally worthless unless backed by empirical data.

On that, I’m very interested in the comparison of Skateway and Zephyr

Talk about different ama design!!

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On 10/8/2019 at 9:43 AM, square top said:

Interesting you say horsepower won't be an issue. At 1.4 x boat length it seems fairly conservative for a 10 metre wide tri compared to say  XL2's new rig at 1.6 x boat length. Standing by to see the power to weight ratio as XL2's is very high at 3.2 tons weight and 60 foot rig for a 38 footer. If Venom is 43 foot and 4 tons it could be considered underpowered by comparison. Greater waterline length and the trimaran factor will come into it. It may struggle against the likes of Rushour though.

FYI, comparison between XL2 and Venom's working Sails, I believe Venom will be 3.2-3.5 T, Jamie's builds a light boat.

I have sailed on XL2 plenty and she does have plenty of horsepower but really struggled for waterline length and with the big rig tended to trip over her fuller oldschool bows.

XL2 is an awesome classic boat but Venom would be long gone on any racetrack.

Rushour has performed very well is and is a super quick boat for what it is, but from where I stand if Venom is not well faster than Rushour I would be extremely surprised. Diagrams not to scale.

Venom Vs XL2.jpg

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Yes,

I would say Venom would be quite a bit quicker  than Rushour inshore but offshore Rushour will be over the horizon in any sort of breeze.

Hopefully they will race her so we can find out!!!

Rushour is getting a bigger rig next year to help light air performance.

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R42 against the Shuttle 39 again - some data - and just for fun with my T-35.

 

                  R42               Shutt39               T-35

Weight:    3300kg         2200kg              1300kg

Beam:        9,58 -            9,7m                    8,2m

Mainsail:     58m2               70m2              58m2

Headsail:     28m2            35 m2                19m2

 

So really - dont think the R42 has a lot of sailplan for the potential.  The S39 and the T-35 has daggers in the floats - the T-35 has assymetric daggers. S39 also two rudders at the floats - its set up for going on one hull. The Seacart 30 is very proned to be sailed one one hull but has the main dagger in the centre - two rudders on the floats.   

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40 minutes ago, SeaGul said:

R42 against the Shuttle 39 again - some data - and just for fun with my T-35.

 

                  R42               Shutt39               T-35

Weight:    3300kg         2200kg              1300kg

Beam:        9,58 -            9,7m                    8,2m

Mainsail:     58m2               70m2              58m2

Headsail:     28m2            35 m2                19m2

 

So really - dont think the R42 has a lot of sailplan for the potential.  The S39 and the T-35 has daggers in the floats - the T-35 has assymetric daggers. S39 also two rudders at the floats - its set up for going on one hull. The Seacart 30 is very proned to be sailed one one hull but has the main dagger in the centre - two rudders on the floats.   

SeaGul, The 42 Main is 70sqm and the Jib is 42sqm.

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8 minutes ago, Lowgroove said:

SeaGul, The 42 Main is 70sqm and the Jib is 42sqm.

Really - looked at Graingers site about this numbers.... at 70m2 thats better for mainsail... 42 jib - thats not selftacking...

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Seagul, we ended up with an overlapping Jib, I will check tomorrow but pretty sure the final sail area is 42sqm.

It has a second Heavy Weather Jib non overlapping on an inner stay that from memory would be around 30-32sqm.

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10 minutes ago, Lowgroove said:

Seagul, we ended up with an overlapping Jib, I will check tomorrow but pretty sure the final sail area is 42sqm.

It has a second Heavy Weather Jib non overlapping on an inner stay that from memory would be around 30-32sqm.

It will be very interesting to follow this boat - the Shutt39 is abit too basic - the R42 has the accomodation that can be acceptable to use as a cruiser and tourer - not around the globe but on extensive coastal trips - and do racing. 

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3 hours ago, SeaGul said:

It will be very interesting to follow this boat - the Shutt39 is abit too basic - the R42 has the accomodation that can be acceptable to use as a cruiser and tourer - not around the globe but on extensive coastal trips - and do racing. 

A return to the original F40 concept?The Grainger is a little oversized and more money than is necessary but Thank Goodness something is going on - what's the progress on the Rapido I wonder?

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