Inboard jet RIBs

[MikeL]

I im interested in learning more about inboard jet boats. Things like cost, speed, durabiltiy, single or twin etc.

If anyone has experiences with these types of drive please let me know. I am more interested in the large size of boat over 7m but any info or stories would be great.

Cheers, Mike

[Alex Brown]

Hello,

If you don't get much of a response here, you could perhaps try asking a company called Ocean Dynamics based in St Davids, Pembrokeshire - http://www.tiex.co.uk/ . They specialise in jet drives on boats larger than 7 metres in length

For quite a few years, they ran (I think) the Thousand Islands expeditions up at St Davids too - it's now been sold from what I see on the website.

-Alex

[MikeL]

Thanks, I will do.

I was planning to tap into the vast knowledge base available on this forum but jets don't seem popular

[Phill]

Driven 5 different jet boats, up to 8m, all singles. Interesting and different (especially astern). Very very manoeuverable (I really must look up the spelling of that word!). 3 levers, never properly checked but seemed higher fuel consumption than same hulls with same engines but legs on them. You really stop worrying about the shallows though. Same sort of speed.

[Jelly]

I've use single and twin jets while helping with testing for my old company. I think they are great, twins are even better than great for manovering and working with ropes etc in the water all around you.
If you search the threads you will find a previous discussion on jets, main point from memory is that if your intact comes out of the water you loose drive and stearage until the water is returned to the system.
Also depending on the drive configuration they can be expensive to run, well ours were but that was down to the choice of parts.

All aside twin jet cat is the most manoverable boat I have ever driven, though getting use to the jet is fun
Jelly

[Scubakid]

I had a 230Hp Yanmar with Castoli jet on a BWM 21 and this was the most manoverable boat I have ever had the main point to note is that the bow will turn in the same direction that the wheel does this is weather you are going foreward or astern. Great fun but not as fast per Hp as a prop.

John

[MikeL]

Thanks guys (and girls)

[Tiger]

Waterjet always going to be less efficient than prop, just the nature of the engineering.

I've not used one but seen a few thrown around (Ribex in Weymouth 10m wheel house rib) and very impressive.

Look at the boats used in New Zealand for the rapids for the tourists and the boats raced in the USA (that 007 used on the River Thames)

As with Jelly, we know a few people who use them commercailly and they are the biz for manoverability at slow speeds, though I would point out that yes they can go shallow, but even with a grill you dont want to suck the seabed into the engine.

If I had the money i'd buy one!

Tiger

[TIM]

The other advantage of jets is that the load on the engine and gearbox is always the same, ie if you are loaded to the max, the engine still pulls the same revs, it just the water jet slipping against water, instead of the prop gearbox under more strain......

Thats why they use them in fast ferrys........

[thewavehumper]

I am presently evaluating a Pacific with a jet drive fitted and I find it incredibly manouverable, unfortunately not yet manouverable in the direction I want to be, but that's beginning to come together.

I am really looking forward to getting it out on the sea and seeing what she is like in the waves, but my first impression is that I really like em.

[MikeL]

What size engine has the jet unit got?