Boat Design Forums  |  Boat Design Directory  |  Boat Design Gallery  |  Boat Design Book Store  |  Thanks to Our Site Sponsors

Go Back   Boat Design Forums > Design > Multihulls
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read Most Recent Posts Gallery Images Search

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 02-22-2009, 01:45 PM
Chris Ostlind Chris Ostlind is offline
Previous Member
 
New Trimaran/Skiff Design

This is the first in a series of four new multihulls that I will be introducing over the next few weeks.

Over the last 6-7 months, I've been doodling around with a design for a boat destined for the homebuilder's market that pays homage to the very cool Weta trimaran out of New Zealand.

This boat is mostly built in 4 mm marine plywood with glass/epoxy laminates inside and out. It departs from the plywood build process with a strip built foredeck and curved transition surfaces in the cockpits.

I've posted an article describing the boat on my website:
http://www.lunadadesign.com/montage-trimaranskiff.html

I'd like to hear any comments that you may have regarding this boat.
Attached Thumbnails
New Trimaran/Skiff Design-montage-bow-water-w.jpg  New Trimaran/Skiff Design-montage-above-w.jpg  
Reply With Quote


  #2  
Old 02-22-2009, 01:55 PM
Doug Lord
Guest
 
Posts: n/a
Does the main hull plane? Apparently, if I understood you correctly, the ama won't support the weight of the boat without being totaly immersed-is that right?
PS- the crossarm transition into the amas looks much better than the Weta...
Reply With Quote
  #3  
Old 02-23-2009, 08:53 AM
grumpy old man grumpy old man is offline
Junior Member
 
Join Date: Feb 2009
Rep: 10 Posts: 9
Location: mackay...australia
oh no not the planing trimaran debate again
Reply With Quote
  #4  
Old 02-23-2009, 09:29 AM
Chris Ostlind Chris Ostlind is offline
Previous Member
 
Quote:
Originally Posted by grumpy old man View Post

oh no not the planing trimaran debate again

No, Grumps... no planing tri debate on this one.

There is a skiff-like main hull, minus the racks, or wings, which may be able to afford some of the characteristics of the typical, well sailed skiff. It all depends on the person driving the boat.

The amas are smallish, at 100%, for what some might call a "normal" trimaran. The ama buoyancy is augmented by the sliding ballast system (crew) who should be able to move about as needed on the tramps to keep most of the heeling moment loads off the amas.

I see the ama role in this design as what some might call a, gust driven capsize preventer. You may even wish to call them training wheels if you're in the right mood. High performance skiffs deal with this capsize situation as a matter of normal sailing until the crew get very familiar with the boat and raise their skill level. For a more family oriented boat, though, I was looking to emulate the Weta example of providing a large measure of enhanced stability so that the boat could be sailed briskly by novices.

I see the owners of the Montage as initially using the ama buoyancy quite a lot when they first get the boat and sicover how to sail it efficiently. As their skills increase, they will probably be more active on the boat and get out on the tramps more, reducing the amount of, ama to water, contact. This will reduce wetted surface and they'll see much faster sailing as a result. Less aggressive sailors will simply enjoy the boat as a trimaran and they will regularly have the Montage heeled over on the leeward ama with less use of the tramps for righting moment.

There is another tangible benefit for the small ama volume of this design. As a boat that is targeted for the homebuilder's market, it's important to understand that not all homebuilders are going to be able to keep the amount of resin used to an absolute minimum. Excess resin use would drive up the overall weight of the boat. Smaller amas have much less of a chance of seriously impacting the overall weight of the boat due to the reduced surface area.
Reply With Quote
  #5  
Old 02-23-2009, 04:56 PM
grumpy old man grumpy old man is offline
Junior Member
 
Join Date: Feb 2009
Rep: 10 Posts: 9
Location: mackay...australia
with there being dozens of old hobie 14/16 cats laying around the backblocks for prices as low as $200 fully rigged wouldnt a 'skiff'type design thet would incorporate the hulls, fully battened rotating rig and kickup rudder system be a cheaper way to go to encourage cheap 'performance sailing
Reply With Quote
  #6  
Old 02-23-2009, 05:17 PM
Chris Ostlind Chris Ostlind is offline
Previous Member
 
H14 rig as option?

Grump,

I looked at using an H14 rig, as the size of the stick and the sails was just right for the boat. Turns out those H14 mast and sail pairs are fairly tough to find. The Turbo jib option is even harder as a used item. That means that all sorts of other rigs, such as the 420 setup, are just as viable and as it turns out, they are much easier to locate.

I do spec an H14 rig as the preferred setup for another boat I have recently completed, but I do not see that design as having the same kind of large scale appeal as the Montage, so finding the available rigs will be much easier.

The Hobie rudder hardware could be a very good solution with a different, lighter weight blade.

I did not consider H14 hulls for the Montage for two reasons.

One: the hulls are just as difficult to locate and when you do find them, there is a good chance that they are spongy and would need lots of stiffening. That would add weight pretty fast and kill the whole notion of where the boat should be headed.

Two: the H14 hull shape has been known to contribute to the business of pitchpoling, they carry their biggest volume well aft of where I would like to see it for a trimaran ama and... I simply do not care for the lines.

There are thousands of H16 rigs, hulls rudders... the whole thing, all over the world, but the rig is stupendously huge for this boat at this particular size and this specific purpose.

I like using H16 rigs for my design work for all the reasons you mention, just not on this one.
Reply With Quote
  #7  
Old 02-23-2009, 08:59 PM
Doug Lord
Guest
 
Posts: n/a
Quote:
Originally Posted by grumpy old man View Post
oh no not the planing trimaran debate again
===========================
In this case I don't see any debate at all: skiffs plane-no ifs ands or buts....
Reply With Quote
  #8  
Old 02-23-2009, 10:23 PM
grumpy old man grumpy old man is offline
Junior Member
 
Join Date: Feb 2009
Rep: 10 Posts: 9
Location: mackay...australia
Quote:
Originally Posted by Doug Lord View Post
===========================
In this case I don't see any debate at all: skiffs plane-no ifs ands or buts....
only when theyre going fast enough... otherwise theyre a displacement v/l like every thing else
Reply With Quote
  #9  
Old 02-24-2009, 03:29 AM
grumpy old man grumpy old man is offline
Junior Member
 
Join Date: Feb 2009
Rep: 10 Posts: 9
Location: mackay...australia
maybe aslightly bigger version than the one youve drawn may tempt the person with the h16 sitting under the mango tree to do some thing with it particularly if he/she has got kids to introduce to the fun of sailing but doesent want to drown them when the pitch pole happens.... I rejected a very good offer on one of my old tornados for that reason ... backm in the early eighties there was a design called a tremolino?? that did a cat to tri conversion using the tornado for the donar parts ... i only ever saw one on the water... and as it was a quiet day the performance was as to be expected ... quiet. This was in the days before assys and prodders and screechers so it appeared to have similar speed capabilities as the old rl 24.. but in a lot more comfort.. no heel I cant remember who designed it but it was in a similar vein top the tramp tri only not folding
ps the hulls of a ply tornado back then wieghed in at 100lbs (each) light for a 20 ft hull

Last edited by grumpy old man : 02-24-2009 at 03:33 AM. Reason: more info
Reply With Quote
  #10  
Old 02-24-2009, 10:59 AM
Chris Ostlind Chris Ostlind is offline
Previous Member
 
Quote:
Originally Posted by grumpy old man View Post
maybe aslightly bigger version than the one you've drawn may tempt the person with the h16 sitting under the mango tree to do some thing with it particularly if he/she has got kids to introduce to the fun of sailing but doesent want to drown them when the pitch pole happens....

I was staring at the ceiling last night and thought of something very much like that, Grump. A big brother tri at about 17' for speedy family sailing would be just the ticket for an H16 rig. Like you said, they are everywhere, well known by the smallest of sailmakers and the mast is not too hefty for a simple raising on the launch ramp, or beach.



Quote:
Originally Posted by grumpy old man View Post
I rejected a very good offer on one of my old tornados for that reason ... back in the early eighties there was a design called a tremolino?? that did a cat to tri conversion using the tornado for the donar parts ... i only ever saw one on the water... and as it was a quiet day the performance was as to be expected ... quiet. This was in the days before assys and prodders and screechers so it appeared to have similar speed capabilities as the old rl 24.. but in a lot more comfort.. no heel I cant remember who designed it but it was in a similar vein to the tramp tri only not folding
ps the hulls of a ply tornado back then weighed in at 100lbs (each) light for a 20 ft hull

Dick Newick's Tremolino was certainly a boat with a very clear vision. There's a whole cadre of enthusiasts around today who cherish their Trems and for good reason. They are fast, fairly easy to sail and have very forgiving tendencies.

I have done a boat with a similar conceptual daysailing approach called the Laguna 20. The main hull is built in marine ply and the rig, rudder, ama hulls and sailing hardware come directly from a Nacra 5.2 or 5.7. The amas fold on a simple, single strut system. The boat easily fits within trailering limits anywhere in the world. None have been built as of yet, but I'm thinking it should be a fairly quick machine in the hands of a typical recreational sailor.

There is also a 22' version of the same design that employs cat hulls from a Tornado, or a host of 20' beach cats with a decided preference for the cats that have large volume with a distinct forward bias to the volume distribution.

There are, literally, dozens of design ideas for boats of this type in the under 22' category... so, there should be a lot of fun in the years ahead as interests and market trends develop.
Attached Thumbnails
New Trimaran/Skiff Design-laguna-20-tramp-bow-obl-w.jpg  New Trimaran/Skiff Design-laguna-20-water-aft-up-obl-w.jpg  
Reply With Quote
  #11  
Old 02-24-2009, 02:42 PM
Chris Ostlind Chris Ostlind is offline
Previous Member
 
Just had one of those insightful, Homer Simpson DOH! moments, when I realized that the website page for the Montage didn't have the specs posted. I had put them in when I originally built the page and somewhere in my editing frenzy, they got clipped.

So, they're up now on the site and also here...

Montage Specifications

LOA 15 6
BOA 12
BOA main hull 41

Sail Area
Main 110 sq. ft.
Jib 38 sq. ft.
Screacher 102 sq. ft.

Displacement 650 lbs.
Weight 235 lbs.


Sorry for leaving that out.
Reply With Quote
  #12  
Old 02-24-2009, 03:49 PM
Fanie's Avatar
Fanie Fanie is offline
Fanie
 
Join Date: Oct 2007
Rep: 2443 Posts: 4,517
Location: Safrica
Looks good Chris, but does the main hull plane?

JUST KIDDIN !

Looking good.
__________________
I am a Boer, not an Afrikaner
Water ! Just gimme water !
Reply With Quote
  #13  
Old 02-24-2009, 10:43 PM
sigurd sigurd is offline
Pompuous Pangolin
 
Join Date: Jun 2004
Rep: 65 Posts: 674
Location: norway
The montage:

1) Humm, what is the middle hull for again? Can you sleep in it?

2) Can you right it alone?

3) Why is the middle hull so wide?
Reply With Quote
  #14  
Old 02-25-2009, 02:14 AM
grumpy old man grumpy old man is offline
Junior Member
 
Join Date: Feb 2009
Rep: 10 Posts: 9
Location: mackay...australia
I ran a h16 rig on a hartley 18 trailer sailer for a few
years ....sailied it single handed most of the time there wasnt another t/s in the club that could get any where near me... I kept the rotating rig 1 reef point for the windy days and no jib for the realy windy days lot to be said for the control of a fully battened rig rarely seen outside of cats in the eightys... now the tornados are out of the olympics there may be a few of those available for conversion soon get yer pencil out chris!!
Reply With Quote


  #15  
Old 02-25-2009, 06:46 AM
redreuben redreuben is offline
redreuben
 
Join Date: Jan 2009
Rep: 310 Posts: 1,004
Location: Beaconsfield Western Australia
Chris O'
you have a great eye for hull shapes and you have potentially plugged some big holes in the diy boat market. But you also have eleven renderings advertised on duckworks that have been "coming soon" for how long now?
The Laguna 20' you have "done" is at what stage, rendered in a computer or built?
I believe you would sell truckloads of plan sets for some of the ideas you have floated, I myself am dead keen on the Backbay/Doubloon concept, so please finish some jobs and stop teasing us.
cheers,
from Oz
Reply With Quote
Reply



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Can anyone help me in skiff design? Satan Boat Design 21 12-22-2007 10:53 AM
Trimaran skiff hybrid frosh Multihulls 6 10-04-2006 02:22 AM
Skiff Design bobby_mcgrath Sailboats 6 08-10-2006 07:52 PM
Skiff design modifications byankee Wooden Boat Building and Restoration 1 05-01-2004 09:43 AM
Help with Skiff Design Bill the Cat Boat Design 2 03-11-2003 09:41 AM


All times are GMT -5. The time now is 09:53 PM.


Powered by: vBulletin Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Web Site Design and Content Copyright ©1999 - 2014 Boat Design Net