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Thread: Fiberglass boat repower survey

  1. #1
    Member Sobie2's Avatar
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    Default Fiberglass boat repower survey

    I've got an older but really nice 23' Uniflite Sportfishermen (raised flush deck) with an old OMC sterndrive, and need I a repower (siezed and crusty old main).

    There are 4 options:
    1) repower and use existing sterndrive (cheapest but this is a Southeast Alaskan boater who frequently ends up in some steep snotty seas)
    2) repower with a new gas sterndrive combo
    3) repower with a new diesel sterndrive combo
    4) repower with an outboard on a bracket. (Honda and an Armstrong)

    What does everybody think? Who has done something like this before?

    Thanks,
    Sobie2
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  2. #2
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    Default Outboard

    I would lean towards the outboard. I'm looking to do it to my 26 footer when/if the old OMC finally quits. Only debate is a single 225 or 250 hp or dual 115's. Nice to have two motors just in case. From what I understand a new 250 hp Honda or Optimax will get better fuel economy than the old v-8 and sterndrive. Besides the hole in the floor would make a great place for a hatch with a nice fish box down below

  3. #3
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    Default my .02 cents worth

    Quote Originally Posted by Sobie2 View Post
    I've got an older but really nice 23' Uniflite Sportfishermen (raised flush deck) with an old OMC sterndrive, and need I a repower (siezed and crusty old main).

    There are 4 options:
    1) repower and use existing sterndrive (cheapest but this is a Southeast Alaskan boater who frequently ends up in some steep snotty seas)
    2) repower with a new gas sterndrive combo
    3) repower with a new diesel sterndrive combo
    4) repower with an outboard on a bracket. (Honda and an Armstrong)

    What does everybody think? Who has done something like this before?

    Thanks,
    Sobie2
    don't like option #1 - for the money a Volvo Duoprop drive is the only way to go.

    option #2 - what I would go with with a Volvo DP outdrive.

    option #3 - I don't know of a diesel engine that is light enough to not want to risk swamping the back of your boat in those snotty seas. I wanted to go diesel in my boat but couldn't even come close - 24' Bayliner Trophy w/ Ak Bulkhead.

    option #4 - most everyone seems to like OB's and points to not having to deal with the engine cowling interfering with their deck space. My backdeck space is approx 8'x8" with only a 30"x30" cowling cover and I use that as a fish/shrimp cleaning table or a cooking table for breakfast/dinner. But I don't have to deal with a single or pair of outboards hanging off the back - that takes up MOST of the stern and eliminates all that fishing area. If you go with the OB idea I would lean towards one Large OB instead of two smaller ones as just one of them won't get you on step in case of an engine failure so you might as well just use your kicker. However your kicker HAS to have enough thrust to be able to keep you pointed in the right direction if needed during an emergency. Lastly I have not done a cost analysist but inboard motors seem to be much cheaper to replace than OB's but require more maintanence.

  4. #4
    Member captaindd's Avatar
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    Default

    Outboard with bracket. Suzuki makes the best outboard with the best warrenty.

  5. #5

    Default

    I repowered my 24-ft Bayliner from 305 2-barrel to new 350 4-barrel. At the same time, got a new outdrive. Got them both as a set at an auction so got a good price. How much would it be to set up your rig for an outboard? And isn't a stern drive setup cheaper than a large outboard?

  6. #6

    Default

    Back around 2000, I repowered a 1976 24ft Fiberform (I know, why?) with a brand spanking new 5.7l Volvo (chevy 350) and duo-prop outdrive. Cost about $17,000 installed. Basically replacing the same engine, but going from single prop to duo-prop.

    The performance increase was not huge, but was better. Obviously slow speed tracking improved. But there is something to be said for prop walk, and using it for your advantage while docking (single prop set-up.)

    My choice from the listed choices is the outboard and bracket. I'd also second the Suzuki recommedation, if service is available.

  7. #7
    Member moose-head's Avatar
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    Default

    I like hondas because they are hondas. No worries

  8. #8

    Default Stability & Center of Gravity or Weight & Balances

    A consideration should also be, Stability & Center of Gravity or Weight & Balances. The water line as we all call it is sort of what the boat is designed at for weight & balance. That line is what the boat should do or be sitting in a swimming pool, I guess loaded with fuel and water and people, not sure tho.
    Change any factor and you change the Force of Movement
    The ability for a boat to right it's self after a wave or weight move.
    rocks to the right to some degree, then it rocks back to the left, how far to the left and back to center.
    It's a very very complicated subject!
    http://microship.com/resources/cg-weight-study.html

  9. #9
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    Default Rebuillt D3

    If you could get a rebuilt D3 diesel with a duo prop drive you would be in business. They are relatively light and very fuel efficent. I certainly would not buy a new one and install in a boat of that vintage. Failing finding one, new gas inboard or outboard & bracket. How loose are the purse strings? I can offer a few places to look if you consider a rebuild diesel. Outboards seem to be easier to maintain.

    Chuck
    Last edited by Salt Chukar; 12-09-2008 at 20:10. Reason: spelling

  10. #10
    Moderator Paul H's Avatar
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    Default

    I'd lean towards the outboard on a bracket. Getting rid of the engine enclosure on the deck will be really nice. I'm also thinking efficiency wise the o/b will be one of the best ways to go. Yeah, diesel is more efficient, but with what diesel is running these days in the greater installed cost I just can't see going that route.

  11. #11

    Default Consider Before/After Value of the Boat--to You and for Resale

    I have done a lot of research and work on this very subject over the six years I have owned an ocean boat. Not knowing what engine the boat came with (and therefore how much weight) makes it hard to give you a specific answer, and I also don't know how mechanically inclined you are, but I can tell you some generalities:
    Limit your budget to the amount you could sell the boat for after the repower--don't end up with $18,000 invested in the repower on a boat that you can only sell for $17, 900. It is just too much pain and hassle. You would be better off selling yours and shopping for a boat that has a relatively new drive train in it, unless your boat is just exactly what you want.

    If your current engine is a commonly found automotive engine modified for marine use, you can purchase a remanufactured long block for it for under $1700, usually,with a one year warranty. Brand new complete engines can be found on eBay for prices ranging from $3500 to $7500. If you aren't going to do the work yourself, a good marine shop can install one for you for about $1500 labor, assuming that most of your engine accessories are good.

    Changing to an outboard has a lot of good points, but it will be very expensive. Your boat probably needs at least 150 horsepower. Any new single outboard with that much power is going to cost at least $12,000, plus the propeller, controls, and gauges ($700-1200). Then you will have to have the transom fiberglassed up where the old drive went through, and have a transom bracket built and then mounted up on the transom. That process will cost about $2200 if you shop carefully. One of the big advantages of an outboard is that it will self-drain, so you don't have to drain and winterize a cooling system for freeze protection.

    A friend recently purchased two brand new aftermarket knock-offs of the Mercruiser Alpha One outdrives. They cost about $1450 each, delivered up here in Alaska, and they are just the outdrive units, not including the gimbal housing assemblies. You also would need a gimbal housing assembly, which probably costs about the same ($1450). Total cost is less than half the cost of a Mercruiser unit. They look real good, and I have heard reports that they are real good. They come with a great warranty package. You would have to have some new controls ($400-600), and do some transom work to use one of these. The hole through the transom is shaped differently, and the mountings are different.

    You could buy a brand new freshwater cooled complete engine for about $7800 (depending on what engine you choose), and the new drive assembly complete and installed for about $4500-5000.

    Having everything brand new is not only a luxury, it is truly much safer out there in the salt water than trying to get by on used and rebuilt parts. It is also really expensive, and they only stay new with careful use and excellent maintenance.

    There is a huge amount of info available on the internet. If you word your questions carefully, you will find expert advice on every aspect of your question. I suggest keeping a separate file folder on your desktop, and saving all your research in it.

    Good Luck and Safe Boating!

  12. #12

    Default

    Sobie2- Sounds like a fun project. You mentioned that your back deck is raised and flush, so I'm assuming the engine is completely under the deck with no engine box sticking up into the cockpit? If so, going to the outboard will not yield any more deck space. I had a 25' Tollycraft (similar size to your boat) with a flush deck (no engine box) and I repowered it with a brand new Volvo I/O package. It originally had a Mercruiser package with the alpha drive, so the new Volvo outdrive fit right into the hole once occupied by the Mercruiser. If you want a new propulsion system, the gas I/O is going to be the best bang for the buck. When I repowered I really wanted a single 250hp outboard, but it would have cost me approx. $7k-$8k more and would have been more work (I did all the repower work myself). Going with another I/O system allowed me to reuse the clutch and throttle cables, steering, etc. While I had the engine out of the stern, I also installed a brand new fuel tank. I would highly recommend a new fuel tank, new bilge paint, and a general cleanup of the engine room. When my repower was complete, my engine room looked brand new and you could have eaten off the floor. I went with the SX Volvo outdrive instead of the Duoprop drive. Going with the SX (single prop drive) saved me around $1400 initially, it weighs a little less, and I didn't feel I needed 2 props to push my little boat around. Plus, if you need to replace props, the single prop is WAY cheaper than the duoprops.

    So in conclusion, if it were my boat, I would get a new Volvo I/O package, 5.0 liter GXI (270hp multiport fuel injected) with an SX drive. Your boat would perform very well with that package.

  13. #13

    Default

    Here are 2 pics of the engine room after I repowered my boat in 2005 with the Volvo 5.7 280 hp. Boat went 39 mph wot.
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  14. #14
    Member Sobie2's Avatar
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    Default

    Bushboy - the newer diesel pkgs like the Volvo D3 (190hp) actually weigh less than the gas packages

    Skydiver - sterndrive packages are cheaper than the big outboards on just cost.

    Alaskapiranha- stability can be an issue (good point to bring up). In many instances large outboards are hung on brackets on boats with low freeboard in the stern and end up sitting dangerously low in the water even when empty. In my case, that wouldn't be a problem.

    Paul H. - agree efficency of diesel doesn't pay out unless you are really truly putting 100s or 1000s hrs annually. And gas is way cheaper (for the moment). Plus I've seen performance reports on Hondas and a few others that are getting fuel economy that rivals diesel when looking at MPG.

    Midnightsunfun - You are spot on. Don't repower a boat unless you like it or are going to keep it forever, you won't make your money back on it. Diesels do command a premium on resale. This boat is special to me and I am going to keep it forever.

    Powderpro - I really like your pictures you did it right. I have been a faithful to the duoprop idea but if the performance is the same you are correct that the difference in price on the drives ($1400), and props (like $200 vs $700 a set) brings up a huge point in savings and more gas money.

    To all: With the exception of using the existing drive and dropping in a new motor, new diesel or gas sterndrive packages and 225 outboard on a bracket will be in the $20k and up range according to local rates. Work will include new cables and guages, glass work for stendrives on the old hole, and maybe glasswork for the bracket if it isn't large enough to cover the old hole and a bracket will run $3500.

    Thanks to all so far, I hope more people will weigh in on. I am hoping that this project will actually get off the ground so I can be floating by spring.

    Sobie2

  15. #15

    Default outboard conversion

    If you are in SE, call over to Wrangell. There are a few outboard conversions there on Bayliners ect.....also Honda was the local brand on most I talked with so your weight comparisons would be accurate for you. I was wary of going with big outboards in '02 but folks there and in Valdez changed my thought process on this subject. Six season later and would not consider going back unless was going to use the motor commercially and even then???? So easy to maintain an outboard standing up as opposed to the days of on my knees and nose under the deck. Winterizing is a snap also.

    On the duo-prop deal, for what it is worth, I was told when I was looking at an Osprey that it really came into play at high speed as the first prop conditioned the water for the last prop. Overkill in most instances but this boat had two big blocks in it and was capable of 50 mph. Never verified this, only what I was told during the sales pitch. Volvo's website had a primer on duo-props a couple years ago when I looked into their new forward facing drive set up and it agreed with what I was told.

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