Ocean crossing in a 25' cruiser

[moonraker 36]

try white star liners.. for info.. their great at crossing the ocean!

 

[oceanfroggie]

It's not gonna happen - end of

E=MC**2

 

[DAKA]

Will you all stop being so negative, the op has come for help and a little out of the box thinking is required, thats all

This could make it

http://commercial.apolloduck.co.uk/listings.phtml?cid=48

Kite as per Flammings suggestion and a periscope for the first 1/3 journey until enough fuel is burnt so it floats on the surface.

 

[DAKA]

I still believe it can be done either with overloading the boat or towing a tank.

You dont need the expense/weight of a tank.
diesel floats, you just need a bag in a net trawled behind

 

[gordmac]

Would a cat be more fuel efficient?

 

[rbcoomer]

Would a cat be more fuel efficient?

A long rope hooked on to a passing freighter might be better still...

 

[lisilou]

Would a cat be more fuel efficient?

Depends what you feed it.

 

[vjmehra]

Lagoon Powercats I believe are CE A rated, so yes they could!

 

[Gushter]

Lots of good info. Just going back to the basic question.

1. The idea is to do it fast. If it would be at displacement speed, then we'll do it in a sailboat. We know the experience, the soonest we could do it will be in June 2014 but we would need to take a pretty long vacation. It will just be 30 days on the water, it gets boring but may be more romantic.

2. If it will be on a motorboat, then we need to find the optimum between size and fuel consumption. As I mentioned before, we do not need this to be riskless, i.e. a B rating is just fine. I understand now that the torpedo would not work (did some calculations, the boat would really not be able to plane, unless 400+ hp). If we get a bigger boat, then the consumption would be around 1.5 nmpg, if we get a smaller boat we could possibly do 2.5 nmpg. There has to be some best size boat for this trip. This is becoming like the rocket equation, rockets are 98% fuel and 2% useful mass. They use stages because it could not be done SSTO. In this case it may turn out that it is not possible to do at all without some exotic designs, materials, etc.

3. It would be suboptimal to purchase the boat, do some tests then realize it could not be done. It is still OK because the boat would be quite useful and fun as a coastal cruiser but I want to do as much research as possible beforehand. Is there some more scientific books/papers that discuss planning hulls, power, drag and the rest? Any pointers would be helpful.

Thank you,
Gushter

p.s. Regarding the poster who commented on diesel vs. gas, it is you who are mistaken. It is much harder to do this trip with a gas engine - you need to transfer the power from the engine to the water. This is typically done with a propeller. For an overloaded boat you need a large and slow moving propeller to reduce slippage. This means diesel. Gas engines achieve their power at high revs which is great for speed boats but will cause too much slip at the propeller in this case.

 

[No Regrets]

There is a huge difference between being 'Realistic' and being 'Negative'

Crossing the Atlantic in a 25' Mobo? seriously? Anybody who needs to come along to a forum, even a good one like this, isn't up to the job in hand (Which is a huge one!!)

Failure is inevitable.

Even with a world class boat, and top crew, this is going to be dependant on HUGE amounts of good fortune, let alone cash....

It's a no brainer....

 

[Portofino]

I think we know 25 ft is too small ,it a case as just said working out " optimal' size ratio re 5600 kg of fuel
So left of field --- think 1960's early 70 F1cars -the early wings over the rear weels. Hold that image Downforce - now think hydrofoil - bit more help consider 5600 kg of fuel in a 7-8000 kg displacement 40-45 f planner
Fit a hydrofoil a wing thingy under the stern approx 1-3. -m in from the stern to create " hydrodynamic " lift at say the optimal compsumption rate for a 300 hp x 2 planner .SO iT CAN GET UP and plane with the the perceived overload
Cos your going @ 22-25 knot drag @ 45 knots is not an issue and you will not be @ 3700 rpm -more like 2500rpm Eco cruise .
Just a case of doing some calculations on the size of the hydrofoil vs drag vs lift vs displacement .
Boat is going to need some surgery re fuel bladders etc anyhow so glass on a hydrofoil while you are at it?

 

[longjohnsilver]

Thank you for the comments and the advice. By the way, this is not a troll. I like the idea to treat it as a theoretical exercise and let people decide for themselves if they want to take this "unreasonable" risk. Just a couple of comments though:

1. The idea here is to cross for a min amount of time. If crossing at hull speed then a sailboat is a much more reasonable choice and then the Pacific is a more interesting ocean (you end up somewhere nice). I have done Newport to Bermuda once in 47' foot racing boat and once in a 30' cruising sailboat. Both times the wind did not exceed F4 and it was pleasant except for the extra effort on the racing boat where we had to change the sails every 4-5 hours to eak out the max performance so we did not sleep much. So, if the weather is cooperating, I do not see the problem. If anything I see crew tiredness as a bigger problem. Given our objective to do it in less than 8-10 days, there is a much higher chance of getting a good weather window than crossing at hull speed in 25 days. The outboard motor will be a backup in case the main engine breaks down (in that case we would dump the excess fuel to balance the boat better). We are clearly going to have a watermaker.

2. I agree that may be a bigger boat will reduce the risks substantially, so I will look into relaxing that constraint. Something in the 35' range becomes a lot easier but then the fuel requirement multiplies.

3. We have taken into consideration the fuel distribution, the need to manage the tank volume, the freeboard and so on. All of this is manageable but I agree that if we hit bad weather in the first 3 days when the boat will be most overloaded, it will likely break into pieces. However, we believe that we would only launch if we have a solid favorable forecast. Any forum members that have overloaded their boats 30%-50% willing to share their experiences on how easy it is to maintain 15-20 knots in F4 to F5 conditions with the typical long period ocean waves?

Again thank you for the advice, very valuable and may dissuade us at the very least.

Gushter

Buy a sailing boat.

 

[castlevar]

I Have Built a boat that will cross the atlantic.
It Is steel 13mtrs single diesel engine over 4000ltrs fuel with a range of 4000 miles at 6 knots We have proved it over the last 10 years but on short runs about 5 day runs worked very well

 

[Yannis]

Thank you for the comments and the advice. By the way, this is not a troll. I like the idea to treat it as a theoretical exercise and let people decide for themselves if they want to take this "unreasonable" risk. Just a couple of comments though:

1. The idea here is to cross for a min amount of time. If crossing at hull speed then a sailboat is a much more reasonable choice and then the Pacific is a more interesting ocean (you end up somewhere nice). I have done Newport to Bermuda once in 47' foot racing boat and once in a 30' cruising sailboat. Both times the wind did not exceed F4 and it was pleasant except for the extra effort on the racing boat where we had to change the sails every 4-5 hours to eak out the max performance so we did not sleep much. So, if the weather is cooperating, I do not see the problem. If anything I see crew tiredness as a bigger problem. Given our objective to do it in less than 8-10 days, there is a much higher chance of getting a good weather window than crossing at hull speed in 25 days. The outboard motor will be a backup in case the main engine breaks down (in that case we would dump the excess fuel to balance the boat better). We are clearly going to have a watermaker.

2. I agree that may be a bigger boat will reduce the risks substantially, so I will look into relaxing that constraint. Something in the 35' range becomes a lot easier but then the fuel requirement multiplies.

3. We have taken into consideration the fuel distribution, the need to manage the tank volume, the freeboard and so on. All of this is manageable but I agree that if we hit bad weather in the first 3 days when the boat will be most overloaded, it will likely break into pieces. However, we believe that we would only launch if we have a solid favorable forecast. Any forum members that have overloaded their boats 30%-50% willing to share their experiences on how easy it is to maintain 15-20 knots in F4 to F5 conditions with the typical long period ocean waves?

Again thank you for the advice, very valuable and may dissuade us at the very least.

Gushter

To dump the excess fuel??? If you had asked the fish, they would think you are a horrible killer and tyrant.