nose diving riveira

Discussion in 'Powerboats' started by aussiebrian, Feb 25, 2010.

  1. aussiebrian
    Joined: Feb 2010
    Posts: 11
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: australia

    aussiebrian Junior Member

    I was in contact with there office directly, and was disappointed in the level of expertise and assistance. When I suspected that the motor was installed to far forward, and the plans had no warning or notes of such a critical step, I lost faith in there ability to help me. The plans mention minimum/maximum engine sizes but as I reasoned, if there was a note explaining where the centre of balance was on the hull and the allowance to make for various motors, the ten minutes it would take to move the shaft hole to suit far out wieghs the weeks it takes to correct the mistake.
     
  2. aussiebrian
    Joined: Feb 2010
    Posts: 11
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: australia

    aussiebrian Junior Member

    Thanks for the link tunnels,
    your pretty close with estimations, the shaft angle is 15 degrees and from the transom to the centre of the carbi is 2.4m. we loaded nearly 350kgs (ballast + people) and managed to get the boat to kinda work at 40mph but it was hairy and lapping the gunnels when we stoped. Proved the right path to persue, but not practical.
    I really want to say thanks for your help and I will keep informed with progress.

    cheers, brian
     
  3. tunnels

    tunnels Previous Member

    pictures please . ones with detail !!!

    AS i asked awhile ago can you post some pictures of a side veiw of the rudder prop and shaft will need to shift the boat back on the trailer , Also some measurements from the transom ( Inside ) to the coupling on the back of the gear box pictures if the motor and gear box and the mounts etc .
    Theres a whole band of people here including myself that are willing and able to help !! you asked for help but we have our hands tied with the lack of infomation and pictures . Dont be shy post !!!:D

    As i said you will have som mods to do so do more than just shifting the prop shaft crib as much as you can every where . Including moving the rudder as much as possible then bring the prop up as close as is practical and then the strut and the stuffing box and last the motor . If all this makes a good boat then post you exsperiances on Glen -L's sight so no one else gets caught with the same problem . You need to get the motor and gear box as low as possible every little helps with the end result . :p
     
  4. tunnels

    tunnels Previous Member

    As i said i drew it all out on my shed floor and could see the shaft was on a real steep angle and when i drew out the shaft from the measurments you gave it was pretty close to 15 . . The weight thing was just to hold the back down to stop the air from getting under the transom and airating the back part of the hull so you could get some speed up and see if it would hold its self with the bow up . 40mph wasnt to bad and it should have dug it bum down a little when you took off .:D
    Where in Australia are you ??:confused:
     
  5. Oyster
    Joined: Feb 2006
    Posts: 269
    Likes: 9, Points: 0, Legacy Rep: 104
    Location: eastern United States

    Oyster Senior Member

    I see that you may think that the motor is installed incorrectly. Why in the hell didn't you stop? Every single boat has a center of balance. Thats boat 101. When you say that there needed to be a warning label. Well duh, a set of plans gives you locations, deminisions and guidlines to go by. Thats almost like the most recent hysteria dealing with hotdogs. Some folks are telling the country that a warning label needs to be placed on them because they may cause you to chock. Duh, chocking is caused by eating for sure small bits and pieces getting lodged in the windpipe, small bits chewed small enough to swallow.

    In order for folks to actually help you without just speculating, you must answer direct questions. Sometimes several questions are required in order to receive enough information when dealing with builds from a distance. Playing the blame game does not fix any problem or even diagnose one. Dealing with a variety of skills and in almost all builds, wording and terms vary. In your case conversion tables came into play.

    You continue to ignore actual real to life builders. Instead you continue to dodge answering some of the basic questions or provide followup photos and deminsions truefully and directly. What you may also have is a simple fact that your bow framing can be too large or even the bow decking too thick also causing the simple notion that with additional materials, thickness and the likes and the type of materials is causing the bow to be heavy.

    I don't know this without asking questions. The principles at Glen L do not know this either until they also ask followups. In your particular case, this is where we are at now. It maybe a pain for you to answer simple questions and your frustration level become too much to deal with some of us peons. But you must go back over some simple and basic questions so that someone maybe able to point you to areas that may fix your problem. Sure the problem may require some serious repairs. But for one and all, anyone capable of building a boat and have it float and run on top surely must be able to make things right, and simple by comparison. Hell we have recalls every single days on products engineered by professional people, and many are always open to listen to consumers.


    But you have zero right to bash anyone at Glen L for the lack of response to you! I am late to this thread. But numerous builders have sucessfully built this boat. You have actually received some followup directly from the owners since Jan. and now you are receiving replies and have full attention given to you by real world builders. The problem is not our fault or the fault of anyone in California, no different than McDonalds providing hot coffee to someone and they spill it in their lap.
     
  6. Oyster
    Joined: Feb 2006
    Posts: 269
    Likes: 9, Points: 0, Legacy Rep: 104
    Location: eastern United States

    Oyster Senior Member

    Several more photos, at the fourth frame from the stem, these shot is showing what appears to be about the same beam as the sixth station going aft and a fuller shape all the way through the bottom. The engine placement appears also to be in the fulliest portion of the bottom too. I maybe a bit off here. But until we get some hard numbers, I am only weighing the several options that makes your hull different than so many others. Thanks for your patience to consider the time to help you hopefully to fix the boat. There are ways to deal with this too without destroying what you have now. But I will await further responses for now.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  7. aussiebrian
    Joined: Feb 2010
    Posts: 11
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: australia

    aussiebrian Junior Member

    hi all, oyster, tunnels
    Sorry I have been absent, but i have some more photos that may shed more light.

    the distance from the inside of the transom to the shaft coupling at the back of the gearbox is 1650mm. In the gearbox connect photo, this displays how much clearance the is between shaft flange and the shaft log seal (35mm). The photo is terrible, but the distance between the prop and the rudder is 310mm and the shaft angle 15deg. the photo shows a 4 blade prop, but we have tried a 3 blade with no improvement.

    oyster, I seemed to have touched a nerve reading one of your posts, my appologies. I maintained all along that I followed the plans. If there was a dimension there, I measured it, cut it and fixed it. On the plans (have you have seen them?) there is a dimension on where to drill the shaft hole, 48" from the transom. Apparently, I have since found out, that's wrong, and everybody who has built this boat successfully, and there is quite a few, ignored this dimension and determined there own. It seems to be common cyberspace knowledge, but it never made it to a glen-l webletter, forum post, and worst of all an ammendment to the 40 year old drawings. I'm a builder by profession, if a client, engineer, council or who ever changes the job because it won't fit, cost to much, will fall over, a note is made on the documents or new documents issued. That's the thorn in my claw over this issue. I'm not blaming glen l for my mistake, I made it, it's mine and no one else's but I do hold Glen l responsible for not updating documentation.

    I wish to thank everybody for there help, think I know what I have to do, so I'll get started and do it and i will get back with the results. Incedently, just a question Oyster, do you think gayle's forum I.D. would be pearl?
     

    Attached Files:

  8. tunnels

    tunnels Previous Member

    Welcome back !!
    I think you need to get a nice clear place on your shed floor and draw out full size what you have incuding the frames and everything else from the front of the engine to the inside of the transom !.
    With a differant color superimpose the new dimentions over the top of what you had and you can see what you need to make all things work .
    I would look seriously at shifting the rudder while you are about all the shifting of things .
    Take it back as far as you can so you steering still works properly .
    Now from the front leading edge of the rudder all you need is the length of the hub of the propeller plus 10mm that will be the end of the shaft !! so the prop will come off when and if you have to change it for any reason . Now the strut only needs 20mm max from its aft end to the hub of the propeller !!
    Now lets go the motor and gear box end ,looking at the photos i would guess you could get the motor back so the aft end of you coupling is very close to the HULL frame ( do a measurement and make sure it is less than your 300 mm or by the time you shift every thing you could still have 15 Degrees shaft angle ) !. The whole excise is to move the motor back but still be able to drop the shaft angle at the same time .At this point disreguard thinking about the shaft length that you have now . The clearance between the tip of the prop to the bottom of the hull needs to be close to 20 mm or a little less. If its to close it will be noisey !! no damage just the noise it makes as the tip of the prop goes past the hull . I would even consider a 12 inch prop instead of the 13 inch prop to lift the shaft up a little more ,every little could help to get the shaft angle down as much as possible , 11 Degrees would be good or even less if its possible !
    Please note everything i have written are suggestions . it is your choice what and how you do this job , But drawing every thing full size is criticly important:D
    A boat designer friend and myself draw everything full size on his design studio wall on a drawing board we set up years ago when designing tunnel hulled race boats , Means you are able to stand back a good distance and look at things from differant angles , it has worked well for us !! plus you have the actual size and dont have to scale measurments .
    By the way you have made a nice job of the boat and the motor install , Even with these teething problems you will end up with a boat to be proud of thats for sure !!
     
  9. Typhoon
    Joined: Mar 2009
    Posts: 125
    Likes: 8, Points: 0, Legacy Rep: 150
    Location: Australia

    Typhoon Senior Member

    I think you need to do some CG calculations now, before you go further.
    I also think there is something that looks finer in your hull around the windscreen area, as Oyster has hinted at. It looks as if your chine dips into the water further back, which means less buoyancy forward.
    I'd try and find somewhere with lifting equipment and lift the hull with straps, positioned so the hull lifts flat. If you lift the hull dead flat and drop a plumb bob from the hoist hook point, there is your CG.
    A local truck owner with a two tonne HIAB could do it for you right at home too. An hour's hire tops. Once you have CG and if you know the boat's total weight and engine/trans weight to within 25kg or so, you can calculate movements in CG easily.
    Then you can play with moving engine mass back and calculate the difference without tearing the boat up and KNOW where it has to go.
    None of this is very difficult, but a little time consuming.

    Regards, Andrew.
     
  10. Nova SS
    Joined: Mar 2010
    Posts: 6
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Bedrock, Ontario

    Nova SS Junior Member

    How did you drill the shaft hole? Did you mount the strut in the proper location and use it to guide the drill or did you just take the dimension off the plans? If you used the strut is it in the location indicated on the plans? The picture below shows the absolute best way to drill the shaft hole, IMHO, it will put the hole exactly where it should be. Is this how you did it?

    [​IMG]
     
  11. Oyster
    Joined: Feb 2006
    Posts: 269
    Likes: 9, Points: 0, Legacy Rep: 104
    Location: eastern United States

    Oyster Senior Member


    Aussie, if you wish to have an attitude and be closed minded,, that is not my problem and few can help you. Its quite possible that with a lot of these projects and issues, sometimes folks can't see the forrest for the trees, the very reason I have spent a lot of hours looking at photos, some that you have provided in an attempt to give you a detached opinion from any in house response given the extreme difficulty of being so far away that you have received from the original owner of the company. These problems require a working and congenial relationship.

    I am three thousand miles away from Gayle. I have no vested interest in their operation other than a decision because of my own experiences to defend the fine relationship between thousands of customers in a sucessfull business venture since 1953. Sure no business will please everyone all the time. This may quite be one of those examples, the further I get into this poorly performing project.


    I also like challenges, which sometimes includes disecting snippits of information into an organized spread sheet in order to come to a reasonable and hopefully a workable fix, sorta giving back to the boating community of the people coming along after me and passing along information in this case that may help you find a working compromise without a lot of destruction and reconstruction if at all possible. If you are indeed an engineer, I bet that for your effort you get paid to provide your imput or opinion unlike me. My opinion is worth what you paid or will pay for it. Discount it if you wish.

    Gayle has indeed been a Pearl to so many people and have to her credit multiple newsletters and several editions of books to their family's credit thats been sold to boat builders that have never built one single GLen L plan, Building with Plywood. Their contributions to the industry is quoted across a wide range of forums and the books are probably in just about every single person's library that has done their own homework before venturing out on their own to build a small craft.

    You an ingeneer or builder,, For me and all of my warts and mispeeled words, I have personally built for 39 years, forget about the ones from a few plans, almost all the hulls by eye including 1600 hp engines in custom hulls, one off too and serviced more boats than I can remember and have a pretty good handle on peformance issues of hulls even though I have not built this particular hull. But the principles are all the same in wharped bottom runabouts, my specialty these days. [now I will remove my arm from around my shoulders]:D :cool:

    So now back to the topic at hand. I do not and did not have any hard information to go on from you and did not wish to confuse your interactions with others and only wished to assist you after you had built a pretty nice boat which turned out to be a poor performing proven hull. Thats not anyone's problem but your own, since the Rivera is a proven hull.

    With you information in hand and then go back to the actual plans, I can also compare your imput which may narrow down an area from my point of view as I did in two forums and several posts. You have yet to provide any measurements of the hull, a number that is important. The photos of your boat are at odds to known performing hulls, especially looking from the bow aft. While we can only trust numbers and reliable imput from you, moving and shifting weights IMO is difficult and I am leaning towards this not making much of a difference at the end of the day.

    I also will defend Gayle when I see that she and Glen L has been misreprented, especially since attempts have been made to elicit information and respond with imput since Jan.

    So now that you know where I stand, feel free to continue to ignore the people more than willing to help you as I will do also now that we and others know the rest of the story, photos included. Thanks Tunnels and Typhoon for your posts.
     
  12. tunnels

    tunnels Previous Member

    Its not over till we see pictures of it doing what its meant to do !!Then i will sleep easy again . :p
     
  13. Oyster
    Joined: Feb 2006
    Posts: 269
    Likes: 9, Points: 0, Legacy Rep: 104
    Location: eastern United States

    Oyster Senior Member

    LOL! A perfect boat? Oxymoron. Its over for me and I have never seen a boat that I could not fix either.:D

    [​IMG]
     
  14. pistnbroke
    Joined: Jan 2009
    Posts: 1,405
    Likes: 33, Points: 48, Legacy Rep: 404
    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    On the glen -l site is an offer of a free on line book.......In it its says that if boats of the riviera style are pushed over 50 mph the nose will come down .....and the cure is to move the centre of gravity back..hence the V drive system came into existance ...

    So would deduce that glen-l know of the problem ( not at 25 mph) and the solution.
     

  15. tunnels

    tunnels Previous Member

    I also feel this is a good case where a little rocker in the right place could do wonders as well . :D
    Vee drive would sure as hell fix the shaft angle as well as shifting the motor back a good foot or more .:idea:
    Theres heap of old Woodies on the youtube and they look all a little nose down untill they get a bit of speed on and or have people sitting in the back . Chris Craft and Century boats made in the 40s through to the 50's , love them !!! specialy the ones with the vee drives and the motors in the back . :p
     
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.