Stringers for Retro Twin-to-Single

Discussion in 'Boat Design' started by MAD JAX, Feb 2, 2011.

  1. MAD JAX
    Joined: Jun 2008
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    MAD JAX Junior Member

    I searched the forum and reviewed what has been posted...has anyone actually completed a Twin-to-Single retro-fit?

    The boat is a retired-from-racing '80 Formula 302 and I'm using an Arneson Surface Drive (Borg Warner 1721/ASD-6s type) with -- eventually -- a 450+ H.P. Turbo-Diesel/Multi-speed Transmission, but for now I'll install a Marinized "Pro-Jected" 454 (w/Thru-Transom CMI Elbow-Tops) into a Velvet-Drive as the Mock-Up...the Boat is pretty stout for how much Glass 'n Resin it was both originally fabricated with AND repaired with from past incidence (some of which appears to be Kevlar for it's green-streaks?), and it's to become more of a dedicated Volunteer Safety/Rescue Tow-Boat, with that being the "Pleasure" of it's (and Mine ; ) future operation...a "Work-Horse" of sorts with some nostalgia perhaps!

    The transom has been blanked-out, keel cut-down & re-glassed to accomodate an Oil Pan, and the Outdrive is mounted (see attached pic.), now I need to install Stringers spaced to accomodate the Single Powertrain...If/when the Turbo-Diesel/Transmission makes it in it'll weigh-in at +/-1500 lbs., so that, A/C, a Gen-Set, additional Fuel tanks, Batteries, etc. will more than make-up for C.G. weight lost in the Twin-to-Single conversion...and here's where I'm at:

    I have an 4" x 10" x 8' LVL I'm lookin' to carve-into Powertrain Support Stringers that will mount in-board of the originals. It's obsoletely heavy IMHO and if it ever went 70 - 80 kts. again I'd be more than fine, otherwise I'll tow "Toys" behind it. When operable as "Safety & Rescue" I'll likely Tow/Salvage disabled boats (I'll be seeking advice on that Rigging/structure eventually too), so I think I want its structure bullet-proof strong.

    Then too, I've read everywhere that "Flex" in the Hull is important...adding another pair of Stringers will make that portion of the hull somewhat more rigid...I ask:

    Should I simply fit them in tight with epoxy and Glass-in versus (that AND?) pre-drill, counter-sink, and anchor the Stringers with 6" x 3/16" anodized Lags (where they'll meet at the bulk-head, Hull, and Transom) before glassing everything back in?

    I posted previously in "Fiberglass & Composites", and -- sans response -- noticed this Topic-Category "Design" get's a lot more attention...if this is "Cross-Posting" I'll digress to whatever Forum-Thread is deemed appropriate by The Forum.

    Please know that Your knowledgable Experience and Opinion shared would be greatly appreciated, Thank You!

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