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Thread: fibreglass vs larger plate ally

  1. #1

    fibreglass vs larger plate ally

    Hi not trying to bring up this same old fibre vs ally battle. Iím looking to upgrade from my Haines V17c and wondering what size a decent plate ally boat would need to be to give a comparable ride for anyone who has had reasonable experience across both (wouldnít consider non-plate ally boats like quintrex etc).

    Always in sharp choppy swell where I am so a good ride is a must - worried to steer away from a 17-19ft fibreglass and go say a 20ft ally in case Iím disappointed with the performance but wondering if Iím discounting ally too quickly. Thanks

  2. #2

    Re: fibreglass vs larger plate ally

    Jarrad, just keep one thing in mind. If ride is your worry, there's no substitute for weight. I'd have my boat made of steel if it was feasible.

  3. #3

    Re: fibreglass vs larger plate ally

    Ride is a product of design more than material, a big, heavy near flat bottom glass boat will shake your teeth out, a very deep V, narrow one will ride good, but be unstable, there is not many deeper V alloy boats around, there's a few that are better, so, unless you go the complete opposite and go for a cat, then you are compromising, go for a ride in as many as you can.

  4. #4

    Re: fibreglass vs larger plate ally

    Thanks - yes am extremely fussy on my fibreglass boats and generally only consider 21degree deadrise or steeper as have always been happy to compromise stability for ride - obviously beam comes in to play as well so I factor this in. I see so many people go production Ally such as Barcrusher and I wonder whether they are happy to compromise ride for the other benefits available to them, or they simply donít realise that there are better options available for an improved ride. I guess it depends on what you are using it for.

    I could choose to drive a bit slower - but donít see any fun in that 😃

  5. #5

    Re: fibreglass vs larger plate ally

    Quote Originally Posted by Jarrad stevenson View Post
    Thanks - yes am extremely fussy on my fibreglass boats and generally only consider 21degree deadrise or steeper as have always been happy to compromise stability for ride - obviously beam comes in to play as well so I factor this in. I see so many people go production Ally such as Barcrusher and I wonder whether they are happy to compromise ride for the other benefits available to them, or they simply donít realise that there are better options available for an improved ride. I guess it depends on what you are using it for.

    I could choose to drive a bit slower - but donít see any fun in that 
    From my experience only mate, I had a Bar crusher 560C (615 I think the model is now) and went fibreglass and wouldnít go back. No offence to anyone that owns one as it served its purpose for a number of years and had many memories etc. But getting older I chose a softer ride. I canít comment on all other plate boats just my experience.
    Matilda

  6. #6
    Ausfish Platinum Member
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    Mar 2015
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    Kalbarri, WA

    Re: fibreglass vs larger plate ally

    I'm with Noelm on the subject of materials--in theory, the only real difference plate makes over fibreglass ---IN THEORY----is that plate will always transmit more noise, at ride or at anchor. At anchor is certainly a consideration if you planned to sleep on board, for example. Weight certainly has a role to play, as well. But where plate falls down, IMO, in the smaller sizes is the inability to get the same subtlety of underwater shape. Welded plate is generally unable to be shaped to the more sophisticated hull shapes. It's all about the entry, and the transition to the final amount of deadrise. And running strakes also play a large part--people have tried this with ali, but simply welding some angle along the hull just isn't the same. Take a close look at the strakes on differing glass hulls--older Haines, for example , are glaringly different to Bertram/Caribbean. They both work, with their individual hull designs, but that doesn't mean that variations in design do not matter. It all has to work together.
    Now, on the subject of deadrise. Simply making a fine entry and keeping it all the way to the transom is not the answer. Look at 615 Barcrushers--constant deadrise, eyeballing it. Sort -of works, but introduces bad effects like the way they absolutely slam into anything on the bow quarter, , because they are effectively presenting a big flat surface to that wave. Horrible. Painful, and I've spent enough time on one to understand them. Straight ahead? Not too bad actually. That spray deflector ( they call it a chine ) throws sheets of water out and down, but, if you are heading slightly into the wind, a lot of that comes straight back at ya. At least BC's ratio of beam to length is OK--there seems to be an obsession with making the smaller platey's "big boats", by making them too wide for their length--result? You can't have a good transition between entry and transom deadrise, so they effectively become flat bottomed. Then you add the requirement for a self-draining deck So you have to raise the deck. Then you have to raise the height of the sides to get freeboard, so you end up with a high COG. You now have a fat, short, high little tank with a miserable ride.

    I believe you cannot get a good ride on a plate boat until you get to at least 7 metres. At that length, a good builder doesn't have stuff with good beam/length ratios, ( partly because of the need to stay within trailerable widths, if nothing else) and can get a bit of good transition in the deadrise. But then the argument of weight comes into it --you actually narrow the gap between glass and ali as you go larger, because you simply have to go the heavier gauge aluminium for everything structural. Ali can actually weigh more. So that much-touted "advantage " is gone. As for deadrise, don't get too hung up on It. it's not the be-all and end-all of specs, it has to work in with everything elase.


    So, after my usual long-winded response, where does this leave you? Short answer, I very much doubt you will get a 20ft platey to charge into a short sea as well as your V17c. It may be better in some other aspects, but you would really need to seatrial specific boats on shitty days to really know if you will be happy, I guess.

  7. #7
    Ausfish Addict disorderly's Avatar
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    Re: fibreglass vs larger plate ally

    Hi mate, where are you using it, for what purpose and whats your reasoning in going from glass to plate alloy...?

  8. #8

    Re: fibreglass vs larger plate ally

    Yep, pretty much sums it up, it's all about compromise, if weight was the governing factor, then simply add ballast.......but it's not all to do with glass boats being heavier that makes them ride "better" it's shape.

  9. #9

    Re: fibreglass vs larger plate ally

    Ranmar and Noelm covered most of it I think.

    With modern fibreglass techniques and light weight composites that get rid of wood/ply in the builds most of the glass boats are of a lighter build than plate ally boats.
    Democracy: Simply a system that allows the 51% to steal from the other 49%.

  10. #10
    Ausfish Addict Chimo's Avatar
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    Jun 2006
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    Gold Coast

    Re: fibreglass vs larger plate ally

    Ride will also be affected to a great extent by the speed you choose to travel.

    Also trim tabs will overcome the shoulder slap / bang and this was the case in my Vagabond and so too in my 5.6 Express a soft riding non plate Al hull.

    If you want a soft ride consider fitting trim tabs and go slower.
    What could go wrong.......................

  11. #11

    Re: fibreglass vs larger plate ally

    I have owned, driven and been in countless boats from 3mtr tinnies to 40ft Cruisers.

    I agree in part to some of the above in that a 7mtr platey seems to be the right scale / ratios.

    Mine is 6.2 ( 21ft 6 inches ), but has no chines on the hull and with a nice entry, I often gets comments like " jeez this is the smoothest platey I've ever been in ". ( It is a super Vee hull, big reverse chines from midship to aft )

    Having said that, the skipper has a major impact on the ride.. in my opinion.

    I also had a 17ft Nova which I thought punched well above it's weight ( same hull Mustang / Haines )

    I have been in some 6 plus mtr glass boats that as Noel says, rattled my back teeth. Again, it depends on your skipper.

    IMO, a V19ft Haines with a pod and some serious Horsepower would be the ducks nuts. Then again, so would a Seafarer Vedette 21ft with an inboard and Hamilton Jet .. hahaha ( yep, I've been in one of these monsters... wow. )

    I am more than happy with my platey for plenty of reasons. Ride, power to weight fuel savings, beach launching, tow-ability, etc.

    You talked about weight, consider a platey with a few crew, and a xos fuel tank etc... you have weight.

    Do some research on smooth riding platey's and let's not forget, these boats love heading into a sea, so up the throttle, down the trim and hold on.... yee haa.


    LP
    Last edited by Lucky_Phill; 23-04-2021 at 03:52 PM.
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  12. #12

    Re: fibreglass vs larger plate ally

    Thanks guys great info - v19 with a 200hp is actually my boat of choice between not too big to manage but great ride. Have one in mind if I can get the minister of finance to agree. Have been in a 17ft nova and agree it rode great - very comparable to my 17c. The above tells me Iím on the right track for what I want with glass - being a boat that will handle sloppy sharp swell with reasonable comfort. Always outside and to be honest a bad riding hull would add a lot of discomfort and time to the journey - very lucky to get even a reasonable smooth day in my realm

  13. #13
    Ausfish Platinum Member
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    Mar 2015
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    Kalbarri, WA

    Re: fibreglass vs larger plate ally

    The whole topic of the skipper having a lot to do with it is a whole other subject. No matter how you trim some boats, they are just bad. When I first got my Caribbean Reefrunner, I was following the standard dictum of trimming the bow down with the tabs to "keep the bow down" in a sea. After some experimenting, I realised that this was not necessarily the way to go. Maybe with some hulls, not with this. It likes to get the bow ( not a fine entry) up a bit, so you are working the deeper vee amidships. This just makes some hulls slam. This one likes to get up and land on the aft half, soft as you like. With a hull of this pedigree, you can actually trim out out, with zero tabs, and drive it like an ocean racer at stupid speeds, it just gets better as you get braver. Then you get a wrong one which is jarring. I have kept up 30 knots straight into a short 3 foot plus sea racing a 24 ft Noosa Cat to a bait ball in a competition, I don't think he believed it. I'm still, after 3 years, finding the best way to drive it. If it get really, really sh**ty,short, steep and nasty, which happens a lot in WA, I can then use some tab, and just do 14-15 knots into it, on the autopilot, pulling back the throttle if one rears up over eye height, because there will be a big hole on the other side. It actually planes at a hair over 12 knots on full tabs down.
    They are all a bit different, some very much so, and you need to know how to drive YOUR boat for the best results.

  14. #14

    Re: fibreglass vs larger plate ally

    Agree with ranmar850 here. I have been in some boats that are either bone rattlers at any speed or just plain wet boats.

    Another matter to consider is the balance of the boat, balance of weight on trailer and also side to side balance for those timers you get some """" hang time """" over the shorter waves. You always want the craft to land ass first and level.

    Noted is my boat loves the rpm heading into a sea with it's bow trimmed down, this also gives it the soft landings ranmar speaks about.

    I won't name names, but I've been in a very popular glass craft at 6.25mtrs in a very small chop and swell, and to put it politely, it was like driving a 4 x 4 over a corrugated road and no amount of trim in or out could fix it.

    I still believe the skipper has a major impact on how most boats handle the seas. I think Jarrad is on the money with a V19 and 200.

    Oh, I have been in 7.4mtr plateys that will knock your fillings right out of your teeth... again, won't name names.

    Budget & intended use will be your terms of reference for this project.

    LP
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  15. #15
    Ausfish Platinum Member
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    Mar 2015
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    Kalbarri, WA

    Re: fibreglass vs larger plate ally

    I personally find the use of trim tabs a complex subject, at least on my boat. I went from tabbing right down in bad conditions, unsatisfied, backed them off, experimented with combinations of motor and tab, stopped using them altogether for over 12 months, went back to small applications at times. I wouldn't offer anything more than the most generalised advice to anyone on a hull other than my own. if someone asked me whether trim tabs were a must on a Reefrunner, I'd say no, nice to have, but not as necessary as some say they are on all larger hulls. And Lucky Phil sums it up with his last sentence--intended use and budget. If you plan on regularly running it up on a gravel beach, or spend a more than average amount of time navigating through a maze of shallow bommies looking striaght into the sun, stick to tin.

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