Subject: Re: [harryproa] Re: Ex40 Light
From: "Rob Denney harryproa@gmail.com [harryproa]" <harryproa@yahoogroups.com.au>
Date: 4/16/2020, 8:39 PM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

 

G'day,
Sorry I have not been contributing.  I had hoped I could do so after figuring out the rig with no track cars or mast bearings.  
Slowly getting there, have figured out how to keep the sail tight against the lee side of the mast using hoops big enough to allow the sail to be hoisted and lowered, how to control twist on a rectangular sail and getting a decent shape from a flat, low cost materials sail.    Pretty sure this will be the rig on the prototype cargo ferry, due to start as soon as the lockdown ends.  

Also been working on solid glass alternatives to foam cores for the hulls, tender and beams to a) save cost (20mm-3/4" H100 PET foam is $US24 per sq m from China) and b) increase the toughness. Several ideas, but testing is slow.  
More on both of these as it happens.

From the thread:
An interesting electric engine option, either in the hull, under the bridgedeck or on the tender. https://www.navigaflex.ch/e/products

Rob, you had said "The above assumes internal (ww inside lw) telescoping which will mean some changes to the deck layout."
Did you mean lw inside ww? so the tender, between the lw beams would slide under the ww hull?
Or would the ww inside the lw mean teh boat would need to attach to the bottom of the lw beams?

My mistake.  WW inside lw allows the tender to hang from the lw.  It is also stucturally better as the bigger part of the beam takes the bigger loads.  Lw inside ww requires some deck changes.  
I have not looked closely at side by side, or over/under, but apart from the looks, both have potential. 

 And who knows, maybe Rob and Steinar will draw up a new, beautiful, streamlined beam design that renders my objections moot.
Neither beautiful, nor streamlined (maybe less drag), but the latest thinking on the cargo proa beams is to make them as a truss.  Slightly deeper and wider than the carbon/foam/glass ones so that we can use fibreglass rods for the truss.  Either make the rods ourselves, or buy pultrusions at retail price of$AUS12 per kg, which is what i pay per kg for infusion resin.  Buying from the manufacturer may be cheaper than buying the materials to make them ourselves.   

On Thu, Apr 2, 2020 at 8:31 AM Mike Crawford mcrawf@nuomo.com [harryproa] <harryproa@yahoogroups.com.au> wrote:
 

Ha, hows having dreams come true feel Mike?

  I'll let you know when it happens.   ;-)

  Many apologies for the delay.  November through March is normally my busy season with software development, and this year I inherited two additional projects.  Email, group chats, and anything of the sort has taken a back seat.  Now that things have eased up, I have time to ponder fast-and-light multihulls.

  So, after five months of time to ponder, I've flip-flopped several times before coming back to my original position.

  My personal goal: 

    - A permanent retractable motor sled underneath the ww hull, with the motor itself being aft of the cockpit when retracted
    - A simple winch, crank, or even set of blocks and a cleat, to raise/lower it
    - The motor is accessible for basic maintenance from the cockpit
    - Tramps between the cockpit and the lw hull


  Reasoning:

    - This is the lightest, fastest, cheapest way to go
    - I'll daysail 95% of the time without a dinghy on board
    - I'd like to be able to expand/collapse on the water without changing motor controls or moving the tender
    - There's more under-cockpit clearance this way than if we try to cram the tender underneath
    - And drive a single unit onto a bunk/multihull type trailer at any launch ramp

  The stock Ex40 design is truly brilliant, and other than the sled, I'm not sure I'd change a thing.

  Fortunately, nothing has to change other than building in mounts for either option.

   Add the permanent tender/sled if you'll use it, go with tramps or a roll-out flat deck if not.

  Which means that now much of my pondering will go back to ways to implement boat electronics, chartplotters, wind meters, and nav lights on a bidirectional boat.

  Thankfully none of that really affects the boat design.

  So now I have to fill the gap between today, when my dreams have been answered with a boat design, and the future, when this design shows up in my life.

  Which, while inconvenient, is still neat.  No other boat meets my criteria for speed and safety, so pinning down the general design is in some ways a miraculous first step.

        - Mike




'.' eruttan@yahoo.com [harryproa] wrote on 11/1/2019 5:12 PM:
 

Did someone sneak a disassembled pic onto the Ex40 page?

| The T40 is 4.7m/15'5" long x 1.8m/5'10" wide. As drawn, the boat would telescope to 4.35m/14'3". The tender would sit under the telescoped bridge deck clear of the water is it was 500mm/20" deep.

And MFW! there is a telescoping drawing? Where would one find this? I know there is a todo list, but just attach it to the message you big tease. 14'3"?

| Access to the motor would require a hatch in the cockpit floor.

When collapsed? That's gonna be a head down bitch, right? Or is the hatch big enough to climb down and sit in the tender?

| Assuming it was wet up correctly, a single line would winch the boat in and out, with the tender locked in place. It could then be lifted lowered as required. Or, the boat could be telescoped with the stern down, even while motoring.

Ha, hows having dreams come true feel Mike?

| The above assumes internal (ww inside lw) telescoping which will mean some changes to the deck layout. Over/under telescoping would require a major redraw, resulting in a somewhat different boat, I think.

And you got the sexyier beams too Mike.

| I'm not sure of this answers all the questions asked as the post has disappeared from my email and is not on the Groups page. Please ask again if I have missed anything.

Missing message is here https://au.groups.yahoo.com/neo/groups/harryproa/conversations/messages/13886

Everything answered I think. 20" beam clearance was the number right?
Dies that seem low?

| The Chat group move is also on the top of the 'to do' list. ;-)

Looking forward to it.

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Posted by: Rob Denney <harryproa@gmail.com>
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