Click for Burger Click for Walker Click for Nordhavn Click for Cheoy Lee Click for Mag Bay

Trim Tabs vs. Interceptors

Discussion in 'Stabs, Tabs & Gyros' started by DOCKMASTER, May 11, 2020.

You need to be registered and signed in to view this content.
  1. DOCKMASTER

    DOCKMASTER Senior Member

    Joined:
    Feb 26, 2012
    Messages:
    499
    Location:
    Ketchikan, Alaska
    Curious to get some feed back if there is any speed/fuel advantage to going with an interceptor system vs. trim tabs? I have a 54' Donzi SF and at cruise speeds I run with the tabs full down. I gain speed and efficiency while tabbing down until I'm full tab down. Makes me wonder if I wouldn't benefit from larger tabs or possibly interceptors instead of tabs? I'm not really in need of roll or stability control so mainly looking at speed/efficiency. I'm sure there is a fine line of having too much tab but I'm left wondering if I would benefit from more since I always use all I've got. Of course, I'm referring to running in normal to calm sea conditions with tabs full down, lest someone scold me about how to use trim tabs :):)
  2. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    12,502
    Location:
    Fort Lauderdale
    I have run several fast boats with interceptors like the 45' Hatteras EX and they work very well. I am running a new 52' Manhattan at 20 knots and they work fairly well, BUT I think tabs may give more stern lift. If you're running tabs full down, sounds like you may be a bit undertabbed…….now with the new engines and lighter weight and new prop design, I would be inclined to run the boat as is, see how it performs and then change them next haulout if necessary.
  3. DOCKMASTER

    DOCKMASTER Senior Member

    Joined:
    Feb 26, 2012
    Messages:
    499
    Location:
    Ketchikan, Alaska
    Yeah I won't do anything until after trials and this season regardless. Just starting to look at options and seek input. Some of the research I've seen suggests the Interceptors provide more lift than tabs then others say the opposite. I've had problems in the past with the hydraulic cylinders on my tabs breaking but it's been a few years now without any issues. I figure if I do need to increase the tab size the Interceptors might be a cleaner and easier install. I also like the idea of less stuff protruding off the back of the boat to foul fishing gear. But it all comes down to what will provide best lift and speed/fuel efficiency as the primary driver.
  4. Maxwell

    Maxwell Senior Member

    Joined:
    Sep 16, 2010
    Messages:
    131
    Location:
    Milwaukee, WI (MYC)
    I "have" a set of Interceptors completed, but waiting to get on a plane from AUS for our Cat C12 715hp powered Tiara 42 Open. The original MI props had some cav burn when I bought the boat used that we've been chasing so finally decided it was time to replace... With the current setup, we were running 28.5-29kts @ 75-80% load, burning 50-52 gal/hr with maybe 30% tab. Once they finally arrive and we're able to splash the boat to test, I'll post our findings.

    Max
  5. DOCKMASTER

    DOCKMASTER Senior Member

    Joined:
    Feb 26, 2012
    Messages:
    499
    Location:
    Ketchikan, Alaska
  6. Maxwell

    Maxwell Senior Member

    Joined:
    Sep 16, 2010
    Messages:
    131
    Location:
    Milwaukee, WI (MYC)
    Apologize for the confusion... I was talking about Veem Interceptor propellers not interceptor tab system. We still have the stock Bennett tabs on the boat.

    max
  7. DOCKMASTER

    DOCKMASTER Senior Member

    Joined:
    Feb 26, 2012
    Messages:
    499
    Location:
    Ketchikan, Alaska

    No worries. That's pretty funny though. I just put Veem Interceptor props on my boat as part of my complete Repower. Trials are scheduled to start on 6/8. If the Veem's perform half as good as they look things will be fantastic. They look like beautiful pieces of jewelry on the bottom of my boat :):)
  8. PacBlue

    PacBlue Senior Member

    Joined:
    Jan 9, 2009
    Messages:
    1,941
    Location:
    Dana Point, Ca
    I have to agree with J , run with the tabs you have now first to see how the weight change affects everything, the reduction in weight may slightly shift your CG forward and up resulting in a flatter running trim and maybe , hopefully, less than full tab required.
  9. mapism

    mapism Member

    Joined:
    Aug 9, 2008
    Messages:
    507
    Location:
    Sardinia
    I just noticed in this photo of the latest 100 footer launched by Permare that they installed interceptors rather than trim tabs from the factory, and this thread popped to my mind.

    Wondering if anyone had a chance to make any further experiences/comparizons, in the meantime?

    [​IMG]
  10. Pascal

    Pascal Senior Member

    Joined:
    Feb 29, 2008
    Messages:
    5,281
    Location:
    Miami, FL
    Interesting. Lazzara eliminated trim tabs on some of their boats including the 84 i run. Instead there is a 1/4” strip of SS at the edge of the transom where tabs would be. Pretty much a fixed Interceptor. Works very well as the boat pops on plane with almost no bow rise at 1500 rpm and 15.5 kts. Doesn’t seem to create a lot of drag even at high speed. 1950 fast cruise is 26kts...
  11. rtrafford

    rtrafford Senior Member

    Joined:
    Jul 13, 2019
    Messages:
    606
    Location:
    Ft Lauderdale
    Trim tabs that extend beyond the transom as opposed to being set into a hull pocket are amplifiers of a following/quartering sea. I like the design of the Interceptor.
  12. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    12,502
    Location:
    Fort Lauderdale
    I think traditional tabs provide more stern lift on the slower boats that need help (more stern surface area) to stay on plane. On faster boats that solidly stay on plane without the use of tabs, and the tabs just add more speed and better running attitude, the interceptors help and they do a good job at stabilizing the boat. Traditional tabs seem to do a better job at correcting list, on boats that routinely list when on plane (FB MY's mainly). It really depends on the hull design, type of boat, and mainly the cruising speed. 30 knots and above the interceptors are the clear winner, below that it really just depends on the above mentioned factors.
  13. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    12,502
    Location:
    Fort Lauderdale
    While Lazzara's tend to run pretty flat and this works, I'd prefer interceptors as you can go with 0 and raise the bow a bit, or put the tabs down further at slower speeds to stay on plane or in rough seas. I prefer to have some adjustment to the running angle.
  14. Pascal

    Pascal Senior Member

    Joined:
    Feb 29, 2008
    Messages:
    5,281
    Location:
    Miami, FL
    Hatteras used to recess the trim tabs in hull pockets. Not sure if they still do, probably not. When I repowered my 53 I removed the originals, closed the pockets and mounted 54x12 on the transom following Bennett’s recommendation. Big difference in running attitude
  15. Pascal

    Pascal Senior Member

    Joined:
    Feb 29, 2008
    Messages:
    5,281
    Location:
    Miami, FL
    .

    True. And you could reduce drag a little.
  16. rtrafford

    rtrafford Senior Member

    Joined:
    Jul 13, 2019
    Messages:
    606
    Location:
    Ft Lauderdale
    Wow. My 53c had the pocketed version, and were very rarely used. Had I thought of extending the running surface as you did, I might have given some considerable thought to that...
  17. rtrafford

    rtrafford Senior Member

    Joined:
    Jul 13, 2019
    Messages:
    606
    Location:
    Ft Lauderdale
    ...I did, however, like them tucked in with the pocket versions when fishing in deep water, not protruding, be it for fish, lines, or wave action.
  18. Pascal

    Pascal Senior Member

    Joined:
    Feb 29, 2008
    Messages:
    5,281
    Location:
    Miami, FL
    I was looking thru the file I have on board which includes a detail log starting from day one in March 1970 and covering the first 12-15 years.

    In 1971 the original owner had 4” added to the original trim tabs... I was also amazed to see that around the same time they recorded A 17kts top speed with 8V71Ns. Yes naturals. Now the long doesn’t say how it was measured... no GPS back then. Maybe times along a measured mile...
  19. mapism

    mapism Member

    Joined:
    Aug 9, 2008
    Messages:
    507
    Location:
    Sardinia
    In principle I agree with the objections of Capt J to such solution, but pretty sure it's hard to beat in terms of simplicity and durability!

    1/4" is by how much those strips extend under the transom border, I suppose.
    Do you possibly know also the other dimensions, like the steel thickness and the total heigth, including the part which is (I guess) bolted to the transom? Besides, how extended are those strips horizontally?

    In the above Amer 100', they look wider than you would expect from traditional trim tabs.
    Practically as wide as the whole transom - centreline aside.
  20. MBY

    MBY Senior Member

    Joined:
    Dec 17, 2009
    Messages:
    63
    Location:
    Newport Beach, CA
    We are using Zipwake interceptors on our 33' CC's and our 42' express. They are nice in the sense that they are compact and I the case of our 42 you won't rip them off when backing down hard on a fish. We had some servo issues and they seem to be very finicky if torqued down too tight on the hull but otherwise they have been reliable. They do take a bit to get used to as they react a bit differently than traditional tabs; they are much more responsive I've found. Performance wise on our 33's the interceptors have done better than traditional tabs.