Trailerable expedition boat

[Mickldo]

Here in OZ there is a huge market for plate alloy boats compared with other parts of the world. I work at a boat building shop http://www.platemaster.com.au/ that builds plate alloy boats.

I personally want to build an expedition boat for myself. I want to be able to head up north and travel around the top of Australia by boat.

The main design criteria are

- 2.5m beam (maximum legal width to tow without oversize signs)

- 3500kg on the trailer (maximum tow weight of my Cruiser)

- diesel powered (just a fan of diesels, no other reason)

- accommodation for myself, wife and daughter

- long range capability

- self sufficient in terms of electricity, refridgeration, etc

- shallow draft

- ability to rest level on the bottom if the tide goes out (big tides up north, 8m+)

- hull strength (I've seen what happens when boat meets rockbar, not pretty)



Now I normally build plate boats so I am more than familiar with their strengths and weaknesses so I am definitely going to be going with plate alloy. I already own a BOC 250R MIG which is what we use to build most of our boats at work. We also use Eutectic MIGs and TIGs but in the spots I need these I'll borrow one of the welders from work.

I love the hull design we use at work too but I know that their might be a better hull for my needs than our normal one. I have been looking at Catamarans too.

A cat will sit on the bottom flatter than a monohull but the design we use has a planing plank so it is better than conventional hulls in this area.

The 7.3m boat we do comes in at about 3500kg on the trailer but that is with only normal amounts of fuel and water on board. I reckon I'll need to get down around the 6m mark to have enough weight spare for all the extras I want. The 6m is also cheaper to build, easier to tow, cheaper to power, cheaper to run, etc. We did one 6m hull (not on the website yet, I'll find some pics at work tomorrow) in a half cab and although it is a little cramped I reckon it would be big enough for my needs.

The max HP for a 6m (according to AS 1799) is 185hp so my preferences for engines are Yanmar 4BY180Z or a Steyr MO174V40. These are to be driven by a MerCruiser Bravo II leg.

I'll go into some more details tomorrow but it is bed time now.

[Mickldo]

Gee, I waffle on a bit don't I?

OK, let me explain a few points.

I love the boats we build at work, there is absolutely nothing wrong with them but there is a couple of design things I want to incorporate where there might be a better hull design to get everything to work.

The main design change I want to make is a diesel/electric hybrid motor. The Steyr sales rep came into work and showed me the latest hybrid motor they do.

http://www.steyr-motors.com/products/pdf/hybrid.pdf

This has got me thinking about mounting one of these in the boat. I always wanted to run a heap of solar panels and a big battery bank so this should work OK.

For the electric motor to run at its most efficient I have been looking at hull designs that are more efficient at displacement speeds. Our hull designer has shown me a couple of catamaran and trimaran designs that might be able to be used. I'm still researching this part.

So at the moment I have a couple of options.

Version 1.0

Platemaster 6m hull with custom built cabin and hardtop.
Yanmar 4BY180Z - MerCruiser Bravo II

Version 1.1

Platemaster 6m Hull with custom built cabin and hardtop.
Steyr MO174V40 with hybrid drive - MerCruiser Bravo II

Version 2.0

Some sort of Cat with twin Steyr MO94K33 with hybrid drive - MerCruiser Bravo II

Version 2.1

Cat with some other breed of motors and hybrid drives (eg - vetus )

Version 3.0

A fancy trimaran design that my hull designer showed me with motive power to be decided

[Mickldo]

Mick. I'm sure they would be fine on the blacktop but how would you go in sand or hot country? I've seen Patrols struggle towing big vans offroad and the owners have gone to Canters and been really happy.

When we built boats at Noosa Cat for the SAS, the Army would come down and do the offroad trailer testing. Trailers were tri-axle with Army Landrover Defender wheels. The boats were 8 meter cats and they would just flog em out in the bush behind the Unimogs. Most fun I've ever had towing a boat. Actually it was the only time I've ever had fun in a Unimog. Haha. Guess when your not paying for the gas and damages > who cares.

BTW Have been looking at your boats more and more and haven't seen anything better anywhere. Certainly miles better than the one in the pic. I think it was about 21' but that's only a guess. Also I think the wheels on the trailer were 16" Landcruiser rims to give you an idea of scale.

The 6m Platemaster hull I plan on using (if I go with version 1.0) weighs about 2500kg on the trailer whereas the cruiser can tow 3500kg legally. While towing 3500kg boats on the highway down your way I can maintain 110km/h on the Nambour hills.

I could've gone with the 7.3m hull we do which weighs 3500kg on the trailer but I reckon that is pushing it a bit close especially off road. This is the main reason I chose the 6m.

I don't want to go any smaller than the 6m. It is the smallest I'd be comfortable with offshore.

Trailer wise we are looking at building our own aluminium boat trailers at work. We already do aluminium racecar trailers at work ( http://www.allweldmanufacturing.com.au/ ) where we use a special aluminium extrusion that we get custom made. Tyres would be the same size and type as the cruiser, preferably with the same wheel track.

I'm also looking at a full skid trailer rather than multiroller.

[Mickldo]

Here is a link to a hybrid Cat. Way bigger than I want to do but along a similar line.

http://www.dsehybrid.com/

[whatcharterboat]

Hi Mick. Hope you didn't think I was paying out on the Cruisers towing ability. I'm sure you know alot more about what they are capable of, than I do.

Anyway have you got anymore info on the Steyr hybrid, power outputs? prices? electrical consumption etc?

[Mickldo]

The main design criteria are

- 2.5m beam (maximum legal width to tow without oversize signs)

- 3500kg on the trailer (maximum tow weight of my Cruiser)

- diesel powered (just a fan of diesels, no other reason)

- accommodation for myself, wife and daughter

- long range capability

- self sufficient in terms of electricity, refridgeration, etc

- shallow draft

- ability to rest level on the bottom if the tide goes out (big tides up north, 8m+)

- hull strength (I've seen what happens when boat meets rockbar, not pretty)

By using an inboard rather than an outboard I will be able to use a heat exchanger for hot water. The alternators on inboards are usually a bigger capacity than outboards too.

Because of my want to be able to rest level on the bottom I want a sterndrive leg so I can trim and tilt it up enough so the hull will sit flat on the delta pad/planing plank.

I am hoping that having the electric hybrid motor as well will give me extra range. The diesel motor will recharge the batteries while underway and the solar panels can recharge while at anchor. The motors can run independently so hopefully that will provide an extra source of redundancy. Of course if I smash a drive leg I am stuffed. Maybe this might be a good thing for twin smaller motors in the Cat version, two separate drive legs.

[Mickldo]

Hi Mick. Hope you didn't think I was paying out on the Cruisers towing ability. I'm sure you know alot more about what they are capable of, than I do.

Anyway have you got anymore info on the Steyr hybrid, power outputs? prices? electrical consumption etc?

Hi John.

I am waiting for an email from the sales rep in regards to pricing.

http://www.steyr-motors.com/index1.htm

http://www.mcintyre-equipment.com.au/steyr.html

The Vetus link I posted before has some info on the hybrid drives they do.

[Mickldo]

Apparently the electric motors do about 5-6knots. Run time will depend on the number of amp hours in the battery bank. You are supposed to be able to use the same batteries for the house batteries and the electric motor batteries.

I reckon if you could make the hull shape more efficient at displacement speeds you would be able to either get a higher speed out of the motors or to extend the run time. This is why I have been exploring the idea of Cats and Tris.

[whatcharterboat]

Have talked to Macintyre before when I was researching for a replacement motor for the other electric boat I worked on. They are only a few 100 meters from my oldies place in Brisbane. The original motor in that boat got wet through the faulty bilge pump. So I pulled it down and marinised it. It was only an industrial pump motor to start with. That is a DIY way out of it but no where near as good.

I got some guys in Narangba to make up some stainless braided ponytails for the brushes, replaced the bearings, fitted all S/S bolts and made a S/S brush gear cover, then resealed the windings and luckily it was all still OK. I suppose a motor like that would still set you back a couple of grand new and then you still need a speed controller, etc. The ones you buy like the VETUS come with raw water cooling and all the control gear as a complete kit (electric only I talking here not hybrid)

Vetus have a lot of experience with electric propulsion. Have been making electric bow thrusters for years so I'm sure they've got it worked out. A few years back I saw a big electric outboard that they were marketing but I don't think it was too successful.

If you ever go the way of a hybrid or electric with diesel charging don't forget to factor in the battery life into the equation. If you only get say 5 years out of a set it would soon add up.

Also once again the PVLs would be worth considering in this application cause you can walk on the them, in stead of the ones on that boat from Florida

[Mickldo]

I know different hull designs work better at different lengths but this is the boat that got me thinking about using a Cat for this boat. Voyager 1040 review preview It is a 10.4m boat that is way too big for my needs but the hull design is very interesting in that it needs only very small motors to push it along at a very reasonable speed using very little fuel. It is a sort of cross between a displacement hull and a planing hull. I tried to get a picture of the hull shape but you have to buy the download to read the whole article.

http://www.seamedia.com.au/pub/index.php

http://www.voyagercats.com.au/home.htm