Commercial lobster boat propulsion jet system

Good day all.
Good morning all. On behalf of my friend who is not online much.
My friend owner and operator of his own lobster boat is looking for alternative boat design that would be efficient in shallow waters and is considering marine propulsion jet system equipment with a 500hp Cummins engine on a new aluminum boat 40 feet and from all I've been reading online seems to have lots of disadvantages. Can anyone here provide feedback with a big thank-you.

 

We need more info on the setup in order to deliver anything useful on the subject. Most important; boat displacement (empty/loaded), waterline length loaded, beam (to chines about midships), bottom rise, speed required (empty/full in what sea conditions). There are some important "don't:s" when it comes to jet application. Given the correct info, we may steer you away from the worst potholes.

 

Western Australian lobster fishermen used jet boats for the short Abroholos Islands season and probably still do. I have been out there in propellor boats, picking our way through narrow coral lined channels, when a jet boat would go hurtling past in a foot or two of water.

I never worked any slipways in Geraldton and don't recall seeing one out of the water, but they would have to have a pretty flat bottom, and waters they work in can be violent.

I didn't see much about them online, but the two ports most would operate from are Geraldton and Dongara, and I would imagine most building and sales of jet drive lobster boats would be around those two areas and Fremantle or Cockburn Sound. The catch is commonly known as "crayfish" locally if it helps with searching.

I would imagine several WA naval architects would have designs on hand if the hulls are suitable. Here is a listing.
Used Gbb Aluminium Jet Powered Fishing Vessel for Sale | Boats For Sale | Yachthub https://yachthub.com/list/boats-for-sale/used/commercial-vessels/gbb-aluminium-jet-powered-fishing-vessel/317609

The fishermen who use them there can tell you all about the pros and cons of jets in their particular fishery and you might find some of them in a Facebook group or online forum.

 

Can think of two that were made for the maine coast, one in the 90s with bmg a traktor jet, then another in the early 2000s. Neither were long lived, to my knowledge both were converted to props with some form of fairly substantial hull work. Remeber the one from the early 2000s showing up in the national fisherman publication, then later that year showing up for sale cheap on a brokerage web site. Then a few months later appearing in the background of the "around the yards" segment getting some serious work done. Never a good sign for a new product.


Jets have a trade off, they do have some serious benefits for fisheries like Bristol bay or similar shallow draft net/gear intensive fisheries. I have a fishery that benefits from jets, the boat is really good at what it does. When in deep water running pots or long lines... its worse than my keel and prop boat in every metric. It dominates in the extreme shallow, but is a workout running down a string of gear with even minor tide and a small breeze.

Seems like the twin setups do much better, the jets work off eachother and the boat stabilizes better for running pots.

Best way I can describe hauling pots with a single big jet... think it was top gear in the old days that put put casters on the back of front wheel drive cars to simulate drifting easily. They eventually were able to drive but it was chaos and a full time job to keep the cars pointed in the right direction. Hauling gear with my big single was basically slitht adjustments on the jog lever while manipulating the trolling valve for an optimum run down gear. Big single jet was constant adjustment to the bucket dump and throttle with emphasis on the jog lever and bowthruster lever for extra help... like a kid button mashing a video game controller.

Its a possibility with the modern joystick systems those issues could be solved or made much easier, but at cost and scale of complexity.

 

Good day all. Thank you very much for the feedback apologies for the delay in responding my friend started lobster season and as we all know long hours. After review of countless website in my opinion the big issue I find with jet system is debris blockage and cant see a captain having to deal with this or the time. Im thinking his best option is boat with outboards that can achieve speeed close to 30 knots. the size of boat he is interested is 40'x15'/16' that can load 150 + empty traps of 300 traps therfore 2 initial trips day one.