Jet Drives

[Assassin]

Has anyone any experience of using them?

At this point it is a concept idea for something to interest the grand children now they are old enough to play with things mechanical.

 

[Portofino]

Presume , jet skis or small rib like Williams Etc ?
The underwater inlet sucks in loose items , rope , L jacket straps that are undone and if long hair will scalp them .
Rope is the most popular so pay particular attention to the easy ness of tipping the thing up on its side ,removing the so called protective grill to access the impeller shaft .
Sometimes it’s a mild one just reverse spins off by hand , sometimes it’s a severe wrap and nylon floating type ( tow rope ) it needs a sharp tool to cut it off in bits destroying it as it seems almost welded on .
If they beach it or run in shallow water running a high rpm it sucks up sand , small stones that get through the grill ,these inevitably blunt the sharp impeller blades resulting in blunted performance if they repeat often , or a big bill for a new impeller if it vibrates.
Too much subsequent vibration left unchecked throws a shaft bearing and / or seal increasing the £££ outlay until the little rascals do it again .

Ok that’s the jet bit done .
Next applies to any fast “ toy “with more than one up ,if the operator flings it into a fast turn it will spin out and chuck the passenger out or all out .

 

[PalmaTarga]

Presume , jet skis or small rib like Williams Etc ?
The underwater inlet sucks in loose items , rope , L jacket straps that are undone and if long hair will scalp them .
Rope is the most popular so pay particular attention to the easy ness of tipping the thing up on its side ,removing the so called protective grill to access the impeller shaft .
Sometimes it’s a mild one just reverse spins off by hand , sometimes it’s a severe wrap and nylon floating type ( tow rope ) it needs a sharp tool to cut it off in bits destroying it as it seems almost welded on .
If they beach it or run in shallow water running a high rpm it sucks up sand , small stones that get through the grill ,these inevitably blunt the sharp impeller blades resulting in blunted performance if they repeat often , or a big bill for a new impeller if it vibrates.
Too much subsequent vibration left unchecked throws a shaft bearing and / or seal increasing the £££ outlay until the little rascals do it again .

Ok that’s the jet bit done .
Next applies to any fast “ toy “with more than one up ,if the operator flings it into a fast turn it will spin out and chuck the passenger out or all out .

just as a matter of balance (not wanting a jet v outboard debate), while I agree they can be temperamental I personally feel I would rather have my kids in the water around a jet than a prop, but as I say, that's me personally.

Yes loose items can get sucked into the inlet, as they can get wrap themselves around a prop. Ease of access to the underside should be taken into consideration, but jet ribs for example should be treated a bit like the bigger boats, ie they might need to be lifted out to be worked on and they shouldn't be run in shallow water. If you have a rise and fall bathing platform or a trailer for example you should be fine for repair access. As stated above, hair could potentially get sucked in, but given the option, if you're that close to a powered boat I'd rather that than get my head mangled by a prop. I guess as a matter of caution and good safe practice you kill the power if anyone is in the water next to any boat.

Lets not forget, if you run into shallow water with a propped boat at high rpm, firstly there's a chance to be launched over the bow, secondly, expect a new drive gear and prop. There are risks regardless, treat a jet like it's a prop and you shouldn't run aground.

Yes, jets are a bit over complicated and dependant on age can be a (costly) pain in the arse, that said, once you launch a 100hp jet they are a ton of adrenaline fuelled fun and would entice any grandchild to a boat again and again way more than any tender with an 8hp (which, size wise is the alternative on our boat). Take into consideration the sea state as to where you are based also, if it's a Williams you are thinking of, they tend to get a bit bouncy in any kind of chop.

 

[Sailorsam101]

Go have a look at the red funnel red jets running from Southampton to Cowes..they seem to work very well indeed!

 

[Sticky Fingers]

Presume, jet skis or small rib like Williams Etc ?
...

Also used on bigger boats eg the gorgeous Hinckley Picnic Boat or Oyster LD43. No doubt others. Don't think it's restricted to smaller vessels at all.

 

[Portofino]

Also used on bigger boats eg the gorgeous Hinckley Picnic Boat or Oyster LD43. No doubt others. Don't think it's restricted to smaller vessels at all.

Think Supeheat6K has done a thread recently about trolling .
I know you arn,t , but somebody made a valid point imho about READING the op .

Do you seriously think the above and a “ red funnel ferry “ is appropriate for a grandchild of understanding “ mechanicals “ to play safely on ?

 

[Sticky Fingers]

Thanks for that helpful remark. I'm well aware of the op's point.

 

[Assassin]

No, neither a jet ski or rib, it is something they will design and build themselves and possibly play with. Jets chosen for safety and any water inlet can be guarded.

 

[PalmaTarga]

No, neither a jet ski or rib, it is something they will design and build themselves and possibly play with. Jets chosen for safety and any water inlet can be guarded.

Sounds like fun, do something Colin Furze style!!!

It would be great if you could document the build with the grandkids, I would love to see it progress. Good luck.