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Ideas For Cheap Fast Practical Trailer Boat 
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VERY rough material estimation:

Surface area of foam and double that of thin ply (4mm 3 ply).

Surfaces:

Roof = 2.4x2m
Foredeck = 2.4x2.4m
Sides = 2.0x1.2x7.2m
Bottom = 7.2x2.4m
Cockpit = 4.0x2.4m
Bunks = 2.0x2.4m
Transom = 2.4x1.2m

Total = 2 + 2.4 + 7.2 + 7.2 + 4 + 2 + 1.2 = 26m * 2.4m ~= 22 sheets of foam and 44 sheets of thin ply.

6.8kg per sheet of a typical plywood for this, means an empty hull/cab/deck weight of about 308kg, nice! It'll be more than this from solid woods used for chine, under transom, engine mounts, etc, but that's a nice figure to start from. Add some plastic windows and various fixtures and it should weigh max of about 1 or 2 tonnes all up.

Fred.

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Fri Oct 11, 2013 12:15 am
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Under the deck, and plumbing!

Under the deck we'll have the following:

Engine
Exhaust system
Air intake routing
ECU and wiring
Battery and wiring
Fuel pump, filter, lines
Gearbox
Transfer case
Driveshaft
prop shaft top end
couplings
fuel tank(s) + filler hose
storage area(s)
heat exchanger/cooling system
steering and gear select/clutch

Engine air feed should come from the middle to top of the cabin through a dedicated PVC pipe embedded in the boat. BUT, perhaps it should just feed the engine area, and the engine should suck its air from there to keep it circulating. Perhaps fans could achieve the same thing while motoring?

Exhaust could be dry or wet. If dry it'll need significant and high quality insulation. If wet it'll need thorough thinking to get consistent temperatures and avoid cracking. Being a petrol engine, the exhaust stream should be very clean, so a rear exit (or 2) is OK. It could also be a dual or single side exit, too, though. If no mufflers are used, it could be pretty loud. Using only mufflers would server as a decent insulator for the most part and reduce heat inside the flammable hull. It'd increase weight, but at the back, where it's more OK. If the exhaust isn't sufficiently high up, then it can't really have mufflers in that section Perhaps the transom area could house an up and down again pipe setup. This certainly needs careful thought, as flammable hull + flammable fuel + hot engine could = long swim, or worse. The fuel doesn't make me nervous, however the exhaust system certainly does.

Batteries, one centrally mounted, or two, one on each side. Close to the engine for both access and short cabling for reduced fire risk. Batteries must be in some sort of plastic enclosure with wise ventilation for hydrogen and acid leakage.

After thinking about exhausts, it makes less sense to have the engine forward where I drew it. It makes more sense to put it hard back and have the engine box be part of the transom. Just to keep exposure to hot exhaust to a minimum. The boat could be a bit shorter/lighter if done this way, too. However steering equipment would be a pain to access under the engine.

The FreeEMS box will go as high up in the engine box as possible but very close to the engine for short (reliable, light, cheap) wiring runs.

Fuel pump will be very close to the rail to minimise high pressure hose. The feed and return lines can be as long as necessary. The pump should go down low as they don't suck well.

Fuel tanks should be 200 - 400 (or more) litres and be made of aluminium or stainless steel. It should be possible to remove them without modifying the boat, even if time consuming. EG, remove entire drive line and pull out through centre access hole. Filler could be ultra short in the deck, or routed up high in the side of the boat for convenience and overflow resistance. A balance tube will be needed between the two halves, and a shut off valve should be present on both feeds. A breather will also be required, and should be as long and thin as reasonable and exit somewhere that won't cause discomfort, eg outside of cabin or even outside of hull up high facing down. Tank location will be under the front half of the cockpit deck on each side. If there is room for them to be bigger, it only increases range, and they don't have to be filled right up.

Sea water for the heat exchanger will be drawn in from the centre of the hull forward of the prop, somewhere. It will have a shut off valve on it, which will never be used. Used sea water should drain out the back or side, possibly through the exhaust.

Steering could be cable, hydraulic, linkages. Gear shift could be cable or linkages. Clutch could be cable or hydraulic or linkages. Throttle will probably be cable based. Needs thought.

Storage compartments should be sealed from other parts of the hull and have a sealed lid, too. Floatation compartments should also be sealed and take up any unusable space. The entire engine / drive line compartment will be sealed from all other areas except perhaps tanks (which are in and off themselves, sealed). If there is a lot of excess space (eg sides of drive shaft) bolt in floatation filler could be added. Why all the complexity? If something does go badly wrong, fitting breaks, wave swamps, the less void space in the hull, the better. The more isolated compartments, the better.

A fire extinguisher is mandatory equipment for obvious reasons.

List of hazards:

Leaking fuel system
Leaking sea water or swamping
Heat from exhaust causing fire
Mechanical system catastrophic failure punctures hull/fuel lines/etc.
Foreign body in water impacts hull (unlikely to cause puncture all the way through)

Mitigating risks:

Use quality fuel fittings and hose, routed intelligently, hard lines where possible, short hoses that physically support themselves.
Reliable fittings physically supported for sea water and systems around it
Sealed compartments isolated from each other as much as possible
Short exhaust with good insulation and possibly water flowing through it
If so try to spray water in through lots of small hoses to better cool the gasses, and use s/s pipe
Use drift shaft loops and put metal shields between engine/gearbox and hull with insulation between hull and shield.

Noise: If the exhaust exits under water while the boat is going slow then there is a huge muffling effect. The main thing is that it's not too loud while cruising at high speed. Having it come out low behind the boat helps as the sound deflects away off of the hull.

Breakfast!

Fred.

_________________
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
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FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
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Sun Oct 13, 2013 3:22 pm
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With respect to my exhaust musings, I have some links and further thoughts:

http://www.goodoldboat.com/reader_servi ... xhaust.php
http://www.marinemechanic.com/site/page66.html
http://www.boatdesign.net/forums/boat-d ... post209742

Out of head, collect together down low into single pipe turn directly upward, enter coby style muffler of whatever length fits, out of muffler into 90 and back down again. At the top of the 90, wideband bung and sensor, likely in the side to allow max height for 90. Coming down out of the 90 into a water jacketed pipe the same length as the coby on the up side. Quality heavy insulation from the heads right up until the water jacket after the 90. At the end of the jacket, water enters the exhaust flow. immediately after this is a water muffler box with a single baffle in it. From here the exhaust is cool and can safely travel through the boat with minimal insulation/care and exit the hull using silicone couplers where necessary.

This makes a case for having the engine in the middle again as I wanted, so there's enough room for muffler boxes and riser U bends etc in between.

Next up, pictures of existing boats illustrating nice ideas they implemented.

Fred.

_________________
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Mon Oct 14, 2013 2:05 am
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A few ideas pinched from various existing designs:

1) I saw a T style ladder hanging off of the bow of a boat onto a beach, nice idea. Second thought, reuse, share it with the fittings at the back for swimming.

2) Drop in or slot in table behind engine box to transom to be used as a table for 2 people, one on each side, legs under, portable seats positioned accordingly

3) Think about portable cooking and toilet facilities, not built into boat, but storage for them, and places/fittings to use them.

4) Ensure it's easy to step up onto sides from cockpit, possibly step in the corner near cabin.

5) Rod rack on back of roof

6) Storage along sides up off the deck (keep toe room) and rod rack above it

7) Flood light(s) for cockpit/foredeck, just like a big boat

TODO edit in some pics

_________________
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Thu Oct 24, 2013 1:16 am
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LOTS of random images of other existing boats:

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More in next few posts...

Fred.

_________________
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Tue Oct 29, 2013 5:54 pm
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_________________
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FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Tue Oct 29, 2013 5:56 pm
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_________________
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FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Tue Oct 29, 2013 5:57 pm
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_________________
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Tue Oct 29, 2013 5:58 pm
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_________________
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FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Tue Oct 29, 2013 5:59 pm
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Some of the above I hate. Some have good ideas. Some show what I can't do. Some show what I should do. Take them as you wish :-)

_________________
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Tue Oct 29, 2013 6:00 pm
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