Transom Question

[smllmth_bass]

Hey guys,

So I have ordered my new hull and it will be coming in next weekend it is a G3 1652 vbw. It has a 20" transom on it, I want to avoid building a transom riser and would prefer to use a jack plate make dialing in the motor height easier. I plan on using a Bob's machine Convertable MJ5 2.5″ setback manual jack plate. I am running a 60/40 Mercury 2 Stroke. This jack has about 6 inches of height adjustment in it. Before I order it I want make sure that will get me enough height. This is the first boat I am building myself so I want to lean on people with more experience so I don't make too many f**k ups.

Many thanks!

[Riverjohn]

What does Bob say??

[steelheadfreak]

If you can, try to avoid jack plates. Pushes the motor further back and makes your boats butt sit even lower in the water. It also puts the leading edge of the shoe further back causing more spray. I hate the things and see them as cop-out for not doing the job right in the first place. With a 20" transom, getting the correct height, provided you have the correct shaft motor should be easy. I use 1/8" alum flat bar same width as the transom as shims. Add till the motor is dialed in (I prefer the lower edge of the front of the shoe to be between 1/8 and 1/16" below the hull. Leave shims in or replace with correct height alum square 1/4" tube. Through bolt and good to go. Now are you trying to hang a 25" shaft motor on a 20" transom? Then you may have to weld the square tube to the top of the transom but I wouldn't hang a 25' shaft motor myself.

[smllmth_bass]

Thanks for the reply! Let me give some additional details for my grand plan of attack. It is short shaft motor so it shouldn't be too much of an issue. I do plan on tunneling my hull so that will add an additional couple of inches of height I need to account for. After reading lots of post on here about jack plates and set backs, I planned to extend the hull and additional 3 inches to account for the 2.5 inches added by the jack plate. Would that be a suitable work around? I am trying to do as few modifications to the transom as possible and make adjustments easy because if I go to a bigger motor I don't want to have to do a bunch of additional work. Also, I want to limit the amount of metal work done as I want this boat to be on the water not on the shop and I would like to limit cost as much as possible.

Bob's also sells a 5" Vertical Transom Extension. Link here: https://bobsmachine.com/product/vertica ... -brackets/. This option has less set back at only half an inch but does not have the adjustibility of the jack. Would these be a better option?

[steelheadfreak]

That's a better option than the traditional jack plate. Adjustability is kinda moot point unless you plan on swapping the jet for a prop on the lower unit on a regular basis. If not, why not just set it and forget it? A bigger question though is why not buy a tunnel boat right off the get-go rather than cut and paste a perfectly good hull? Or was it a used boat to begin with?

[smllmth_bass]

The reason I would like to tunnel a new hull is that I want to configure the hulls layout to my specifications. The G3 1652 vbw hulls seem to be the best starting point what I want to do and the best price. They do make tunnel hulls but do not sell them as a lone hull (you have to buy their Yamaha and trailer to get the hull), the other thing is that I just don't like how their tunnel hulls are setup and are very heavy. Their tunnel hulls are listed at a package weight of 1600 lbs and I am planning on keeping my package weight under a thousand. Also, I am not a fan of consoles and prefer stick steering to a steering wheel. My plan is to basically just replace my existing hull with a newer nicer hull that is setup the way I want while keeping my motor and trailer. The welder who will be doing my metal work is extremely capable so I am not concerned about adding tunnel causing issues.

[steelheadfreak]

Yeah the production boat builders like to stick to a program. If you have not yet bought the boat, you might want to look at a custom builder. My buddy just got a new bare bones Koffler 16' with a 60' bottom and its pretty awesome. With a tunnel. With the ETEC 90/60 jet tiller, he came in right about 1000lbs. My buddy supplied the motor and the trailer. Koffler just did the hull. Its a great set-up just the way he wanted it. Not far off the production boat price either for a comparable set up.

[jl8jeff]

I have a Lowe 1652 jet tunnel with a Mercury 60/45 2 stroke short shaft motor. The transom is around 23" but is about 20.5" from the top of the tunnel. I have the motor mounted around 2" above the transom and haven't had any issues. I don't think you would need a riser or jack plate, but if you converted it to a tunnel, you might need a riser or transom extension at that point.

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[smllmth_bass]

Thanks for all of the input guys I really appreciate it. I think a complete custom hull may be a little overkill for what I need as the only major changes I am going to make to the hull will be adding the tunnel and a "stool" that will house my batteries and provide a place to mount the drivers seat and controls. Aside from those things my other modifications will just be adding the gas tanks, batteries, mounting the trolling motor, wiring everything up and laying down the carpet. I am sure I will have more questions as I start putting things together especially when it comes time to drill holes in the transom to mount the motor.

[mitch184]

I wouldn't sweat a jack plate for a second. They work fine for a jet, tunnel or not, just are more sensitive and actually allow you to raise the foot a little more of the time. If you're not swapping from pump to prop a lot, personally I'd just locate the height correctly and drill.

[smllmth_bass]

Thanks for the replies everyone. Ill be sure to post pictures when everything is put together.