Jet foot with a 19ft deepV tunnel hull
Moderators: bman, Chalk, Tom Keels
-
southren4evr
- Posts: 45
- Joined: April 6th, 2005, 12:28 pm
Jet foot with a 19ft deepV tunnel hull
Im thinking of getting a Jet foot for my tunnel Hull 19 ft fiberglass Deep V hull boat ..Does any one have a idea if the tunnel hull will disrupt the water and not let the jetfoot preform as intended to ..ive raed pros and con on Jet foots with Tunnel hulls so just wanted to know yalls Ideas on this Thanks for all your ireplys i hope i get some good adavice
-
Second Chance
- Site Sponsor
- Posts: 385
- Joined: January 2nd, 2002, 8:00 pm
- Location: McDonough, ga
Got this article below by a supposedly jet boat "expert". I run a jet on a flat bottom 1652 G3 and have several friends that have various other configurations. None of them are true tunnel boats. One guy has a high end Snyder custom boat and it kinda sotra has a tunnel. But, the tunnel only extends back up into the hull about one foot from the stern. Hope this helps.
Why A Jet?
I had three reasons for shopping for a jet. a) Our company does sidescan sonar imaging which requires towing a sonar transducer (towfish) behind the boat, and the cable that connects to the towfish is unbelievably expensive. We didn't want it cut by a prop. b) We often have divers around the boat...they're even more expensive than the cable. c) This was going to be our small survey vessel, and we needed to be able to launch and run it almost anywhere. Shallow draft was important.
The boat that I decided on was an 18', modified-vee hull, all weld aluminum, "jonboat", with a center console. Alumacraft and SeaArk make virtually identical boats that even have the same part number: MV1860AWCC. We ended up with an Alumacraft purely because of logistics. The boat design turned out to be a good choice. The boat takes a ton of abuse in stride, has some stability and wave handling ability due to the vee hull, and has a low profile which allows us to get under low bridges.
The mistake that I nearly made in the boat selection was that I almost ordered the "tunnel hull" version of the MV1860. Both SeaArk and Alumacraft offer several of their jonboats with a "tunnel" built into the rear portion of the hull so that an outboard can be mounted higher on the transom, drawing its propulsion water from the tunnel area. With this arrangement, a conventional outboard can be mounted so high that only the skeg on the motor projects below the plane of the bottom of the boat, deriving shallow draft while on plane. I figured that if the tunnel was good for conventional outboards, it would be great for jets. WRONG! During my research into jets, I found two dealers who had sold tunnel hulls and jets to customers who ended up with pitiful performance from their boats. I finally located a mechanic who could explain why. The positional relationship between the water intake foot of a jet outboard, and the trailing edge of the bottom of the boat hull is very important to the proper operation of the jet. A smooth flow of water from under the boat is imperative. The tunnel hull, while on plane, presents a very disturbed flow of water to the jet intake.
Why A Jet?
I had three reasons for shopping for a jet. a) Our company does sidescan sonar imaging which requires towing a sonar transducer (towfish) behind the boat, and the cable that connects to the towfish is unbelievably expensive. We didn't want it cut by a prop. b) We often have divers around the boat...they're even more expensive than the cable. c) This was going to be our small survey vessel, and we needed to be able to launch and run it almost anywhere. Shallow draft was important.
The boat that I decided on was an 18', modified-vee hull, all weld aluminum, "jonboat", with a center console. Alumacraft and SeaArk make virtually identical boats that even have the same part number: MV1860AWCC. We ended up with an Alumacraft purely because of logistics. The boat design turned out to be a good choice. The boat takes a ton of abuse in stride, has some stability and wave handling ability due to the vee hull, and has a low profile which allows us to get under low bridges.
The mistake that I nearly made in the boat selection was that I almost ordered the "tunnel hull" version of the MV1860. Both SeaArk and Alumacraft offer several of their jonboats with a "tunnel" built into the rear portion of the hull so that an outboard can be mounted higher on the transom, drawing its propulsion water from the tunnel area. With this arrangement, a conventional outboard can be mounted so high that only the skeg on the motor projects below the plane of the bottom of the boat, deriving shallow draft while on plane. I figured that if the tunnel was good for conventional outboards, it would be great for jets. WRONG! During my research into jets, I found two dealers who had sold tunnel hulls and jets to customers who ended up with pitiful performance from their boats. I finally located a mechanic who could explain why. The positional relationship between the water intake foot of a jet outboard, and the trailing edge of the bottom of the boat hull is very important to the proper operation of the jet. A smooth flow of water from under the boat is imperative. The tunnel hull, while on plane, presents a very disturbed flow of water to the jet intake.