converting outboard hull to straight inboard?

29chawk

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greetings, new to this forum my hull a 29'c-hawk its not a real downeast design but i have to make do with what i got. Currently she's powered by a 300 suzuki 4stroke and its pretty efficent about 2mpg under light load and calm conditions. but i've really been wanting to put a 6bt 300hp in her, for first off the type of fishing i do the outboard is in the way, secondly i hope to get a little better fuel economy, hopefully better ride in chop due to weight forward, maybe more stable at drift due to lower center of gravity 15degree deadrise. do you think any of these are realistic expectations? does any one on here have any input on how difficult and expensive it is to convert over. anyone have a 28' bhm they wanna trade lol! thanks for any input
 

VPC

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diesel

I think it's an excellent idea but at the end of the day if you aren't doing the work to reduce the cost does the end justify it? Keep in mind that an outboard is to a certain extent more forgiving when riding, with the modification you'll have an exposed shaft and running gear so that's a big consideration. All things considered tanks fuel lines and so on if I had the oppurtunity and was going to keep the boat I would do it, some have been made engine mid ship and depending on the structural integrity of the existing stringers you will have to install an engine bed and perhaps sure up the existing stringers. So briefly you're looking at engine, engine bed, shaft, stuffing box probably dripless, rudder and rudder post, steering, fuel tanks and lines, structural repair of transom, and any structural modifications for the actual installation
 

VPC

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diesel

Some additional notes and also owning a C hawk as well as several other center consoles as well as downeasters I'm speaking from experience; consider this with regards to engines in lieu of the fact that you're primarily a sportfishermen I would research the cummins and I'll tell you why, mainly increased weight and space required for the installation, I would look at yanmar do your homework and you'll probably save over 900 lbs without the gear. Also because of the RPM'S you'll be swinging a smaller wheel, so weight reduction and speed derived from that another factor. Someting to consider when you are adding weight to an existing medium to low shear boat that can be a bit wet. You say that you average 2 mpg at what speed?, as we speak gas compared to diesel is cheaper, I would explore some other ways to improve performance perhaps tabs, prop modifications of which there are some new inovations, discuss lifting rails ,is the engine on a bracket, stretching your hull with a high transom and bracket could dramatically improve the efficency and ride something you need to explore. So it's an important decision but non the less an interesting one. The reality is that a 300 HP engine may be more economical but in my opiniom not all that much, even if you double your mpg it's a long way to regroup your investment. C hawks a great boat that whole NC area is home to many spinoffs, C hawk, Privateer, Parker, Maycraft all semi hybrid workboats not a helluva a lot of bottom on any of them but for the most part their 25 knot boats in most conditions. Downeaster was also out of Marshallberg I think Lookout took the remaing molds that was also a nice "carolina flare" type boat too.And last but not least compare maintenance oil changes, filters, engine zincs and so on.
 

29chawk

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good points, the boat is used for work so i do put alot of hours on her. the new 4stroke outboards are so hi tech one wire in a harness or an error code will leave you dead in the water, i like simple things so diesel power is attractive in that aspect. as you can see the outboard is on a bracket so no transom repairs are needed and im pretty good at glass work so engine beds and boxes and such i can easily handle building. prop shaft location not a clue. the most economical speed for mpg is 20 knts. total cost of the repower is a big factor thats why i mentioned cummins they seem to be quite a bit cheaper than a yanmar around 300hp, i agree weight is surely a factor 900# is a huge difference. I like the boat alot and it handles the conditions in florida very well so id like to stick with it and I plan on selling the 4stroke to help pay for the repower but I start to wonder if it is worth it cost wise or should i sell the boat and look for another that is inboard powered already.

deckk.jpg

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c-hawk1.jpg
 

F/V First Team

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Reinventing the wheel is a hard task, it might be more user-friendly to find an inboard that will suit your needs. Just looking over some google-based images of the 29' I thought one would need a V-drive to get the weight correct but then you'd be stuck with a ginormous engine box. A Steyr diesel might be better weight wise, being basically the same as a 350 chevy in size and possibly weight, I know they are quite light and turn 4400 or so.
 

BillD

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Reinventing the wheel is a hard task, it might be more user-friendly to find an inboard that will suit your needs. Just looking over some google-based images of the 29' I thought one would need a V-drive to get the weight correct but then you'd be stuck with a ginormous engine box. A Steyr diesel might be better weight wise, being basically the same as a 350 chevy in size and possibly weight, I know they are quite light and turn 4400 or so.
See, always a need for V-drives in certain install situations.!!! LOL

Thinking this over with the hull modifications, transom repair, hours involved and cost.........not to mention the weight of a 6BT/BTA and gear.

IMO, I can't get my head around the cost effectiveness of the whole project even if you REALLY LOVE the boat.

Better off to sell your boat 1st and buy a compatable 28-29 footer with a diesel inboard already in it to "spruce up". You'll be way ahead of the $game$

FWIW,

Bill D
 

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Raider Ronnie

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