one prop instead of 2

[FAST FRED]

"Remove both propellers and install a center jet drive of whatever size you want, then if you ever change your mind put propellers back."


"it is 90ft GRP minesweeper, that will have new engine."

I think if he has a spair $100,000 he would be installing a second engine.

At displacement speeds water jets is only selected by military folks ,
who value the shallow draft , more than they value fuel consumption, maint, and installed service life.

FF

[YuriB]

Idea was not to change something in the desigh and simplify the whole concept. Yes i don't have spare 100K, but will find some to put in bow thruster that will improve control over the vessel while docking and at slow speed.

[apex1]

Yuri, install two smaller engines instead of one and you get happy. Leave the bowthruster, no twin engine boat needs that, as long as one has the skills to handle a boat.
you found that nobody here was a friend of your idea, so you should think twice about it.

Regards
Richard

[mydauphin]

Originally Posted by FAST FRED

"Remove both propellers and install a center jet drive of whatever size you want, then if you ever change your mind put propellers back."


"it is 90ft GRP minesweeper, that will have new engine."

I think if he has a spair $100,000 he would be installing a second engine.

At displacement speeds water jets is only selected by military folks ,
who value the shallow draft , more than they value fuel consumption, maint, and installed service life.

FF

I know, I was joking ....

[Submarine Tom]

Yuri,

All the power to you my friend.

For the record, I think it a terrible idea.

However, you think it a good option.

So, try it and see what happens.

All you have to do is remove the starboard (right) propeller and give it a go.

You may want to put a barrel of water on the port side to simulate the missing starboard engine.

Please be sure and let us know what you think after you've logged a few hours .

Tom

[Willallison]

I'm with our submariner here... whip off a prop and see what happens. Ok - most of us are well aware of the consequences, but Yuri obviously needs convincing.
Whilst it's not the ideal set up, I agree with FF - the only real difficulties will arise at slow speed. There are plenty of displacement boats that go around dragging one prop.
Installing 2 smaller ones as apex suggests may indeed be the best work around - though you'll almost certainly have to change to different props at the least.

[mydauphin]

How can anybody have a 90ft minesweeper and want to go with one prop, sideways. It is like buying a Ferrari and putting smaller tires on one side.

[Willallison]

We seem to have missed the most important question here.... why?

[mark775]

Familiar with glacier bay cats? IMO, about the only small cats that work, as they are displacement. The guy who built those is now building cats with one engine to good effect.
The minesweeper will never be a great boat on one off-centerline engine but obviously money is a consideration and props are removed all the time on boats transiting to Alaska to no ill effect. I don't think it'll be all that bad, certainly not dangerous or anything, and the fellow can decide later if it's what he truly wants. I like the two smaller engine option but apparently it isn't one. Re-distribute the load if an engine is pulled.

[apex1]

Originally Posted by mark775

I like the two smaller engine option but apparently it isn't one. Re-distribute the load if an engine is pulled.

Why should´nt that be a option Mark?
It is common practice on almost all conversions of ex Mil. vessels due to their too mighty engines. A prop and gear setup of course has to be part of the conversion.
And the statement in post #7 was pretty clear "new engine", so, I claim my advice to be at least a very sensible and cost effective one!

Regards
Richard

[mark775]

You're right. I was assuming a money problem that fades away with post 7 - and two little ones would be cheaper than converting to one new big one...no question.

[YuriB]

Apex1, original engines were rather huge, low revs and taking almost half of the hull space. Now i will move the smaller Cat 3208 engine further to bow into small compartment but will have to add one more shaft and bearing). I will use the boat as lake cruiser for holiday once a year (for 2 weeks) and all the rest of time the lake is frozen. So i don't see any reason to equip it again as military ship with twin engines and propellers (exept if i get into money troubles and decide to sell it to Somalian pirates for their business))

You may be surprised, but still it is possible to buy in USA Cat3208 (bobtail) with 100SMU for $2800. This is FirePump engine.

[Willallison]

2 weeks per year!!
In that case, do away with both engines and stay in the marina....
Even better, sell the boat and charter for 2 weeks - it would be 1000% cheaper than mooring and maintaining a 90ft boat.
Seriously Yuri... are you having us on...?

[YuriB]

No, i want to have my own boat, not charter. I hate the idea, really.
Mooring the 90ft boat cost 100 euro per month (at least while they are not going to rise the prices). We all here in the North live like this (seriously, all water frozen or weather is too cold for pleasure sailing). In many cases people spend weekends on their boats cooking BBQ and drinking vodka during winter season.
Well,
this is a little bit different from what you call marina, but still..

[apex1]

Yuri
you can have such engine for free at some places.
And your idea of moving the engine compartement is a true nonsense at least!

I like to follow Will to ask: what is your purpose? having wasted our time?