420 Aft cabin underpowered?

Discussion in 'Sport Yachts/Yachts' started by cigars01, Jun 5, 2020.

  1. cigars01

    cigars01 Member

    124
    Sep 1, 2016
    Lake Lanier,Cumming Ga
    1981 Searay 310 Vanguard Express Cruiser.
    Twin 454 Crusaders Direct Drive
    I am looking at buying a 1996 420 Aft Cabin. The boat is powered by the base 7.4 merc engines which I believe are 340Hp each. The engines from service records have been well mainitained and have 635 hours. I boat on Lake Lanier, Ga. My question is: are those engines enough power for that boat?

    Seeing the configuration of how the engines are installed, if you had to repower or pull the engines for any reason, is it possible withoug doing surgery to the salon floor or cabin etc?
     
  2. Stee6043

    Stee6043 Well-Known Member

    Jun 1, 2015
    West Michigan
    1997 Sundancer 400
    7.4L Gassers
    The trusty 7.4's are more than enough for a 400DA. I guess the only downside to the aft cabin is that it's heavier and the weight is further astern. My experience is that the gas powered 400DA is perfectly balanced, much better than the 340 I had with the same power.
     
  3. cigars01

    cigars01 Member

    124
    Sep 1, 2016
    Lake Lanier,Cumming Ga
    1981 Searay 310 Vanguard Express Cruiser.
    Twin 454 Crusaders Direct Drive
    What does the 400 DA weigh. The 420 Ac dry is 27000 pounds.
    Thanks
     
  4. northern

    northern Well-Known Member

    Jan 17, 2007
    West coast Vancouver to Alaska
    380 Aft Cabin 1989 GPS and Charts by Nobeltec
    Twin 454 strait shaft
    We have a 380 aft cabin with twin 454 you will burn 1 GPM at 6 knots. If we were to get a new big boat we would go with diesels. If you do less than 50 hours a year it is good boat.
    Boat will do 22 knots but burn 55 GPH. Boat weight is 20,000 pounds dry we have it loaded and weight is 30,000 pounds.
     
  5. bbwhitejr

    bbwhitejr Well-Known Member SILVER Sponsor

    Apr 14, 2013
    Lake Lanier GA
    2007 44DB
    Cummins QSC 8.3s
    I would say yes. My 44DB weighs in at 28,000lbs and is powered by Cummins QSC 500s at 478hp each and it is no speed demon. Loaded light at WOT I have seen 34mph....I cannot imagine 7.4 gas engines. Had a dock neighbor with a 370 Aft Cabin and I think it had 6.2s. To me, it was underpowered....A 2002 410 Dancer weighs in at 22,000lbs.

    Bennett
     
  6. Stee6043

    Stee6043 Well-Known Member

    Jun 1, 2015
    West Michigan
    1997 Sundancer 400
    7.4L Gassers
    I am a svelte 23,000lbs in my 400DA.

    I slip 2 slips away from an early 90's 45 Viking aft cabin powered by gas engines. Sure, it's a dog, but he's not running up and down the cost of Michigan every weekend. Seems to work famously for him and his family.
     
  7. bfernald0

    bfernald0 New Member

    11
    May 18, 2020
    Marina del Rey, California
    340 Sundancer 2001
    8.2L Mercruiser ECT Horizons
    42 ft is ultimately too big and too heavy for 2 454 engines (they're 310 apiece). That thing will guzzle fuel like it's going out of style. In my opinion, anything 40 and up should be diesel.
     
  8. dtfeld

    dtfeld Water Contrails GOLD Sponsor

    Jun 5, 2016
    Milton, GA
    410 Sundancer
    2001
    Axiom 12 MFD
    Cat 3126 V-Drives
    For Lake Lanier, I dont think its under powered as we never really go that far, and none of the sea rays are over powered. It'll get you where you want to go except the biggest issue on the Lake (and Bennett can address this), is the height of the boat. You'll want to consider going North under Browns bridge and the other bridges on the North end of the lake, as this will limit where you can go. Also consider that the lake is going up 2' at normal pool, hence all the new bridges.

    I'm a 2001 410 w CAT 3126's and we weighed in a 28,500 at the sea trial and I'm sure we weigh more like 30,000 filled with water fuel and all the other stuff that makes in onto the boat. My favorite cruising speed is at 2300 RPM going 20.6 kts or 23 mph burning 19.2 gal/hr and getting 1.07 NMpg or about 1.25 statute mpg. For cocktail speed, I use around 900-950 RPM going about 7.5 kts or 10 mph and sipping a little over 2 gals/hour and approaching 3 mpg.
     
    Last edited: Jun 6, 2020
    cigars01 likes this.
  9. bfernald0

    bfernald0 New Member

    11
    May 18, 2020
    Marina del Rey, California
    340 Sundancer 2001
    8.2L Mercruiser ECT Horizons
    I overlooked the Lake Lanier part. You're probably right. It would be under powered for the Pacific Ocean ;-)
     
  10. cigars01

    cigars01 Member

    124
    Sep 1, 2016
    Lake Lanier,Cumming Ga
    1981 Searay 310 Vanguard Express Cruiser.
    Twin 454 Crusaders Direct Drive
    The engines are 340 hp as per the Searay brochure.
     

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