Red Sea Dive Boat

Cheers BB!

Unfortunately very close to corals at times, and the water at what passes for a jetty is very shallow as well.

From what I understand, jets are more efficient too - which will be important to keep costs down.

 

I just researched your Yanmars and Doen jets.
This is a long way from twin outboards.
Government rules okay with this option?
I sure prefer the diesel over gas of the o/b's.
Only snag might be cost vs budget...

 

The coastguard has only restricted outboards - a fair bit of drug running happens in that part of the world so I guess they are targeting RIB's and other fast boats that hang outboards.

I prefer diesel as well for all of the obvious reasons.

I won't know cost until Doen reopen after Christmas.

 

I just ran through your previous equipment thread and noticed the the discussion about cutting left off in July with no real conclusion. If that is still of interest, Laser cutting may not be the best choice. Laser cutting has some limitations with aluminum due to thermal conductivity and reflectivity. Shining a light on a mirror is not the easiest way to warm it up. The maximum thickness for laser cutting is about 30 mm. There was some mention of water jet cutting, which is what this laser cutting company recommends for thick material. When the company making the equipment recommends something else, they have a reason. There was some mention of cost of laser vs routers. Lasers are inefficient. It takes a lot of power to generate a laser beam. Aluminum is very reflective and most of that inefficiently converted power will be reflected away. Good for steel, titanium almost anything but aluminum.

I don't agree with the poster who was concerned with contamination from the abrasive used. Water jets cut cleanly and can cut almost anything. For my money, water jet is better. Plasma, I have only seen with steel, so I will not comment.

Someone mentioned cutting aluminum with a circular saw using a standard carbide tipped wood blade. There are expensive industrial metal cutting blades and there are cheap off brand wood blades. The expensive blade will outlast the cheap one, but the cheap one will cost 1/10 as much, last half as long and cut just as well. I have cut some of the strongest aluminum alloys around, up to 50mm thick on a 10" table saw with an ordinary carbide tipped wood blade. I have cut 37 mm thick alloy 7068 with a yield strength just over 700 MPa on a portable contractors saw. A steel bar that strong would take the teeth right off that blade. Curved cuts are a problem for a circular saw though.

MIG is probably the best choice for welding. There are some more expensive, exotic ways to weld, if you have more money than most governments.

Alloys, look into ASTM B928 and be careful of the temper you order. There is marine grade and there is the lot that failed the corrosion test and was sold with a different temper designation. I doubt that any mill would scrap 50,000 lb if they could sell it under ASTM B209.

 

RSD,

Why were you considering o/b's?
Cost?

If the Yanmar/jet works economically,
would you consider longer and skinnier
hulls to increase the cruising speed?
No, 12m is a government convenience limit.
Design the pontoons far apart and reduce their individual widths.
This will give you better economy and higher cruising speed.
And improve seagoing capacity with higher freeboard.
But you gotta keep it light weight.
No air compressor on board, right?
One helm ( a flying bridge ) would reduce cost and weight vs two.

Water cutting your aluminum would be preferred.
I'm confident Mr Poleson will know what to do.
I like the idea of using his 12m x 5.5m cat hull.
Just be sure it doesn't surpass the 12m government measuring test.

Would you recess the lift or transom mount it?
Less pitch / heaving recessed, less "prop" wash from the jets too.

How many dive boats do you have now?

Do you operate out of the Sea Dream Hotel or at least in that bay?

 

Hi RSD,

I hope you're moving forward with your project.
I may have some international clients for you.

BB

 

Sorry, what time is it?

 

Brand new dive boat capsizes while being delivered to the Red Sea:

 

Still not happening RSD?

 

Oops looks like I have somehow missed seeing a bunch of replies here - sorry @Dave G 9N and @BlueBell - I will reply to each post individually, but unfortunately things have been held up as I injured facet joints in my neck and then became very ill. I'm just getting back to it now.

 

Lots of good advice there - advice that makes sense too which is always good!

The preferred cutting method would seem to be with a CNC router, next alternative would be a waterjet, and laser as the last option for the reasons that you said. I think that using a table saw etc is probably out as I'm sure that curves will be required.

Getting the right alloy is important - and very important if I end up getting the boat made in Asia - which is looking like an increasing possibility - unfortunately Australia has priced itself out of most manufacturing due to high labour costs and over-regulation making workers unproductive. I'm not confident about getting the boat made in Egypt as there is only one yard there with experience in aluminium boat building and they mainly build for the navy, and they are at the wrong end of the Suez canal compared to where this boat is going to be so that adds complications...

 

a number of factors - cost, simplicity, and plug & play dynamic positioning capability - the Suzuki Duo Prop outboards would be the go to choice I think for outboards if I go that way.

Probably not - for several reasons it is somewhere between nice and essential to have someone living on the boat full time - lack of really protected anchorages is one, security is another, and so the hulls will be used for things like heads, etc etc. Given that I will probably be the one living on the boat I would like it to be a little bit comfortable. To get more cruising speed I might instead look at a simple foil between the hulls as that seems like a fairly low cost way to increase cruising speed, or some design ideas like Myark's catamaran - I'm in communication with him, or inboard diesels to get past the 300hp limit - maybe twin Volvo Penta D6 440hp with stern drives as that will still give dynamic positioning, or inboard diesels with jets if I can find an affordable solution. 440hp inboard diesels might end up with a fuel cost per mile as 300hp outboards due to better fuel efficiency of the diesels - but I don't really know what the fuel efficiency ratio is between diesels and petrol outboards.

12m seems to be a magic number in a lot of places - in Australia up to 12m is once class of commercial captain operator licence that is relatively quick and easy to obtain (possibly too quick - it can be obtained in a week of study with very little time spent on the water), next step is 24 metres and that is 5-7 weeks of full time study.

A beam of 5.5 metres on a 12 metre boat seems optimum for a dive boat, I don't think that a lot would be gained by going to a 6 metre beam - but 5.5 metres should put the hulls far enough apart. Higher freeboard is nice...

Fuel efficiency isn't as critical in Egypt as it would be in other places - diesel is US 35 cents per litre, 92 octane unleaded is 37 cents, 95 is 39 cents (US $1.33/$1.41/1.48 per gallon). Having said that, fuel efficiency is still a nice thing to have as it increases range for a given fuel tank size.

Flybridge is the norm in Egypt due to the heat, or a minibridge up top if you hate the winter winds like I do.

A good compressor setup will add about 1000kgs so that might indeed have to be ruled out... damn it!

I'm pretty sure that he does. Getting him to answer is the tricky part - I might need to call him I think.

12m x 5.5 metres seems to be the way to go, the government measurement test seems to be a bit vague (but that is normal with most things in Egypt), it seems to be length from tip of the bow to transom, but there appears to be lots of room for local interpretation... The best bet seems to be to make the boat about 11.8 metres - but make it so that the bow can be easily extended by a little bit out to 12 metres as the number of persons the boat is licenced for in Egypt is one person per metre...

At the moment I am leaning towards mounting the lift further out from the transom so that it is beyond the props/jets and then fitting a "guard fence" either side of the lift so that divers are protected from the props while approaching the lift once it is in its down position.

I don't currently own any boats there, a mate has two and is looking to add a third one

I don't know the Sea Dream Hotel and had to look it up, but presuming that it is the same Sea Dream that google found then will be operating out of the same bay for the archaeological project, but I'm thinking that for taking tourists diving then the Safaga area seems the better area for a boat - the peninsula gives a bit of protection from the prevailing northerlies, and there is a good mix of dive sites there, and also a good mix of coral species as well - it is a bit of a blend of the species commonly found in the "north" and those found further south, has a couple of wrecks and a few more that might be able to be opened to diving with some negotiation with the navy base commander, etc.

 

I'm trying once again to move forward with the project now - nothing is ever easy!

 

I'm not sure whether it was the cause in the case of this boat, but with the liveaboard/safari boats in the Red Sea that do the 7 days out trips there has been a bit of an "arms race" for bigger boats and more luxurious boats so as they can carry more passengers and make more money - this has led to some boats being horribly top heavy with too many decks up top, and the inevitable happens - the prevailing winds can be very strong at times and they blow straight down the Red Sea - and there isn't a lot of protection. That is part of the reason why I am going catamaran.

 

If you go o/b; your 2nd highest risk to fire is drowning the engines, so go 25” legs or even 30” if possible, but 25” min