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Converting a sporty to outboards

Old 09-05-2018, 06:50 PM
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Default Converting a sporty to outboards

I'm looking at a 95 Blackfin 33 combi. The engines are gone and I'm thinking of putting a bracket on and trying to figure out how much power I will need to get in the low 30s for a cruise? Also any ideas what mite be involved as far as strengthening the transom to take the bracket? Any advice would be appreciated. It seems like a good idea at least on paper any real world horror stories?

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09-05-2018, 08:50 PM
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Put a pair of 425 hp QSB 6.7 Cummins in it and don't mess up a good looking boat. Or just go buy the Viking with the 250s.
Old 09-05-2018, 06:58 PM
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I have to think your two limiting factors will be transom reinforcement and beam of the boat (trips or quads??). It can certainly be done, just about how much time effort and money you want to put in to it.

Id have to imagine a trip setup of any of the new 350s out there should push the boat to a 30+/- cruise. Quads or 400s would just take it up from there.

Otherwise, my primary concern is the depth of hull at stern and how low you’ll have to get the center engine(s).
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Old 09-05-2018, 06:58 PM
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300s probably 350s. Probably heavy and the transom might be wimpy for outboards. My topaz can't even support 200 lbs on a ladder without flexing.
Old 09-05-2018, 08:50 PM
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Put a pair of 425 hp QSB 6.7 Cummins in it and don't mess up a good looking boat. Or just go buy the Viking with the 250s.
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Old 09-05-2018, 10:01 PM
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I get sticking with diesels but all that is missing and we do a good bit of sandbar time and being able to trim up is a plus.
Old 09-06-2018, 04:56 AM
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Originally Posted by Castawaychris View Post
I get sticking with diesels but all that is missing and we do a good bit of sandbar time and being able to trim up is a plus.

Take all the money you were going to spend on the motors. bracket, controls and fuel system and buy a 23' jones brothers bateau. They have to be the ultimate sandbar boat. You will come out much much better both in the short and long term. Tow it to the sandbar with the Blackfin if you have to have both there.
Old 09-06-2018, 05:21 AM
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Originally Posted by Castawaychris View Post
I get sticking with diesels but all that is missing and we do a good bit of sandbar time and being able to trim up is a plus.
Have you seen this?

FS Project Dreamboat - Seacraft Perfection, Transformed Classic Bertram - Florida Sportsman
Old 09-06-2018, 06:42 AM
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Originally Posted by wahoo wacker View Post
Take all the money you were going to spend on the motors. bracket, controls and fuel system and buy a 23' jones brothers bateau. They have to be the ultimate sandbar boat. You will come out much much better both in the short and long term. Tow it to the sandbar with the Blackfin if you have to have both there.
We do a good bit of rig fishing in the gulf so the 23 mite not work for that. Currently I have a 35 cc but looking for a bit more comfort. I have a dock to park at that at times can get a bit shallow and i absolutely refuse to bottom paint my cc so it goes to the boat ramp on Friday out on mon. Theres not enough room to put a lift due to sticking out in the canal. With the blackfin I'll bottom paint it and leave it. It will be sticking out a bit but I dont need a permit for that. Guess I'm just trying to get the best of both worlds.
Old 09-06-2018, 07:16 AM
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I would be concerned about how such a drastic change in weight distribution would affect the ride.
Old 09-06-2018, 07:28 AM
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Originally Posted by Castawaychris View Post
We do a good bit of rig fishing in the gulf so the 23 mite not work for that. Currently I have a 35 cc but looking for a bit more comfort. I have a dock to park at that at times can get a bit shallow and i absolutely refuse to bottom paint my cc so it goes to the boat ramp on Friday out on mon. Theres not enough room to put a lift due to sticking out in the canal. With the blackfin I'll bottom paint it and leave it. It will be sticking out a bit but I dont need a permit for that. Guess I'm just trying to get the best of both worlds.

I was thinking you would keep the blackfin as an inboard (or whatever else you have) for offshore. The skiff stays inside or a few miles out at best but damn its great to take people to the sandbar, just run it up on the beach gently and everyone piles out with all their crap. As a bonus you can inshore fish 4 - 5 people in relative comfort. the sandbars in your area may not have a lot of current but around here is a lot of shallow water getting there and tons of current so the scenarios may be different but taking a big boat to one around here = no fun for the capt.
Old 09-06-2018, 07:49 AM
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Castawaychris; a BF 33 is a very heavy boat. Can it be done? probably... would it work? I don't know and personally, I won't go this route, I would try remans cummins.

A typical BF 33 Combi weights about 20,000 pounds, has a deep v (20 - 22 degrees) and has a beam of about 12 feet. Weight figures vary with engines, as a Cat 3208 is heavier than the 430hp Volvo's it also came with. All in the right place to keep a low center of gravity and balance.

Remove the diesels and you loose about 3,000 - 3,700 pounds. Add OB and a bracket and gain back about 1,500 pounds in the back of the boat. I'll be concerned on engine height.
There's a fellow THT'r who did it in a BF 29 with twin G2 300 E-Tecs and the boat is about 50mph fast. But a a 29 is about 9,500 pounds lighter and has less beam.

Join BF forums and ask there. Members have a lot of BF specific knowledge.

Best of luck and post whatever you decide to go with.
Old 09-06-2018, 08:51 AM
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A friend of a friend did this conversion to a 40 luhrs with trip yamaha 350's and the boat was plenty fast but thirsty compared to the inboard diesel boat. He sold the boat a while back but I think he is in the middle of doing a similar conversion on another 40 luhrs currently.
Old 09-06-2018, 09:11 AM
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That's a lot of work, trouble and expense to go to the sandbar, cheaper to get a smaller boat for sandbars, and then when you outgrow hanging out and drinking, you will still have a nice boat to fish off
Old 09-06-2018, 09:36 AM
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There is one in Greenwich CT I see around all the time with twin evinrudes.
Old 09-06-2018, 09:51 AM
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Guys over 48 will say get diesels under will day go for the outboards
Old 09-06-2018, 11:10 AM
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no offense chris, just being honest, if you like to spend alot of time at the sandbar, a blackfin 33 combi certainly is not the best choice...
best advice, and cheapest, scrap the whole outboard conversion plan, buy an inflatable with a 9.9 and rig up a bridle, drag that beeotch behind you on sandbar days, keep the fin on the hook in deep water and pretend she is a mothership.
if no go on above, it's cheaper to sell the blackin unmolested as she is, then start over with a different ride.
Old 09-06-2018, 12:46 PM
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I am on the Gulf coast and I believe I know the exact boat you are considering. I considered this project back in January. I spoke with Armstrong about a bracket for trips. He quoted me between 8 and 10k depending on options. I really wanted to take it on and add a transom livewell, a mezannine, custom helm and interior as well as a hardtop and generator, full paint, etc. I kept adding it all up and it didn't make sense for me. Plus, I am sure I would have gone over budget by as much as 50%. Good luck and I hope someone takes it on - very nice hull to start with.
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Old 09-06-2018, 01:45 PM
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I saw a similar set up on the Severn River last week. About a 36' sport fish with a single outboard on the swim platform. Boat was grossly under powered and he could not hold course with all the wake action going on near Annapolis.
looked like a waist of $ and time to me.
Old 09-06-2018, 05:20 PM
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Originally Posted by Katrina View Post
I saw a similar set up on the Severn River last week. About a 36' sport fish with a single outboard on the swim platform. Boat was grossly under powered and he could not hold course with all the wake action going on near Annapolis.
looked like a waist of $ and time to me.
I can assure you it will not be underpowered. It will have a minimum of 900 hp maybe 1050 so it will get out of it's own way pretty easy
Old 09-06-2018, 05:25 PM
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Originally Posted by rybovich18 View Post
I am on the Gulf coast and I believe I know the exact boat you are considering. I considered this project back in January. I spoke with Armstrong about a bracket for trips. He quoted me between 8 and 10k depending on options. I really wanted to take it on and add a transom livewell, a mezannine, custom helm and interior as well as a hardtop and generator, full paint, etc. I kept adding it all up and it didn't make sense for me. Plus, I am sure I would have gone over budget by as much as 50%. Good luck and I hope someone takes it on - very nice hull to start with.
The boat is not on the gulf coast but your points are still valid. The guy has a line on a bracket made for that boat for 5k . I'd do most of the work myself but I'm sure it far exceed my planned budget but I sometimes let my determination override common sense.

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