New Project Handling Issues?

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NZjohnson90

Seaman
Joined
Nov 25, 2009
Messages
64
First off does anyone know why I cant put up a new post in the Completed Boat Projects section?

Anyway I have spent the last 12 months Filling, Sanding, Painting, Head-scratching etc. Trying to get my first boat project complete. Christmas Eve was her first outing and although I thought I'd thought of everything I hit a couple of possible problems. She floats and she goes but I am not sure she is handling as she should.

My parents had boats when I was growing up so I have got experience driving but it was a long time ago. I am still new to boating and dont know all the terminology so please bare with me.

The first thing I noticed was when we put the boat in it sat very back heavy in the water to the point the engine well gets around 6inch of water sat in there through the drain hole. This does get better when I get in but still feels arse heavy. Once on the plane the water drains from the engine well.

Secondly, although the boat does plane no problem, if you accelerate hard the nose comes very high before she sits back down. If you accelerate gently it seems to 'plough' and struggle to get up. (or is this just normal and I dont know the difference?

Thirdly I find The slightest bit of chop or wake seems to sort of catch the front of the hull and feels kinda unbalanced, or at the least gives quite a bumpy hard ride. Maybe this is just because it's an old, lightweight boat?

Finally when cornering she feels much flatter than previous boats I have driven, barely leans into the corner at all which feels quite un-nerving if going at any speed, Maybe this is normal for this type of hull, or maybe not?

I brought the fuel tank, Oil Tank and battery as far forward as the cables/hoses would allow and bunged the drain hole in the transom and It did feel better but still not right.

I have put up some pics so hopefully you get the idea.

It could be a case of motor too big, but I have however seen a number of these Glastron hulls around with this kinda size motor so I thought it would be ok. Either way, its on there now and after all the cash and time spent I will have to live with as best I can.

Is it a case of relocating the battery/tanks etc? maybe adding a couple of sandbags up front? or is it more a trimming issue as I don't full understand where I am supposed the have the motor trimmed ( it was all the way down most of the day)?

Or am I just being a grandma about the whole thing and just leave as is?



http://i497.photobucket.com/albums/rr333/kiwigt/Boat/IMG_1890.jpg
http://i497.photobucket.com/albums/rr333/kiwigt/Boat/IMG_1891.jpg
http://i497.photobucket.com/albums/rr333/kiwigt/Boat/IMG_1932.jpg
http://i497.photobucket.com/albums/rr333/kiwigt/Boat/IMG_1935.jpg
http://i497.photobucket.com/albums/rr333/kiwigt/Boat/IMG_1935.jpg
 
QC

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: New Project Handling Issues?

NZjohnson90 said:
First off does anyone know why I cant put up a new post in the Completed Boat Projects section?
Click to expand...
I have sent you a PM on that issue.

Also, for that thread and this one, please resize your pics to 640 x 480 max. Just works better for more browsers and lowers speeds.

Thanks :)
 
trendsetter240

trendsetter240

Lieutenant
Joined
Jun 22, 2009
Messages
1,458
Re: New Project Handling Issues?

Hey there,

I think you have a couple of issues there, #1 from looking at the pics it appears overpowered. This may not be the case but I'm guessing there is not rating plate on that boat or you would know for sure.

The most simple method of determining maximum horsepower is to measure the length of the boat and the width at it's widest point then use the following formula. ((Length X Width X 2) - 90) The number you end up with is the max HP for that boat.

Another issue you may be having is with the trim of your motor. In the pics you are trimmed too far out. Try trimming the engine all the way in then back out a tad before accelerating to a plane. Once on a plane trim the engine out until the prop starts to ventilate then trim in until it stops.

You are right about the weight distribution; this is also very important. Moving the gas tank forward should provide you some benefit. Unless you already have long battery cables I wouldn't worry much about moving them.

As for sand bags I wouldn't go for that. Just going to use more gas than you need in that case. You can find a good balance by adjusting the trim on your motor, moving around the existing heavy items in the boat and possibly changing props to suit your specific needs.

Cheers!
 
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NZjohnson90

Seaman
Joined
Nov 25, 2009
Messages
64
Re: New Project Handling Issues?

Thanks for that, The first few pics while I was going slow are perhaps a little deceiving the motor is trimmed right out but that is because I had just launched from shallow water and I as lowering the motor at the time. Once out in the water properly I trimmed the motor all the way down/in and kept it like that the whole time.

I will try to play around with the trim a little next time and trim out a little once planing. I could get the fuel tank maybe halfway up the boat, so I'll try moving it right into the bow next time.

I do agree in hindsight that the motor may be a touch on the heavy side (johnson 90hpV4), but as I am on a serious budget, and will never need to run at full throttle, I think I'll have to live with it for now.

Would this explain the very flat turning as well? or is thisjust the way thus hull handles?
 
trendsetter240

trendsetter240

Lieutenant
Joined
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Messages
1,458
Re: New Project Handling Issues?

NZjohnson90 said:
Would this explain the very flat turning as well? or is thisjust the way thus hull handles?
Click to expand...

Not sure about the hull, looks like a shallow V hull and should handle some chop without much issue. You should check how high the motor is mounted on the boat. The anti-ventilation/cavitation should be even with the bottom of the hull or up to 1" above the bottom of the hull. If the motor leg is too low in the water you can get handling issues as you described.
 
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NZjohnson90

Seaman
Joined
Nov 25, 2009
Messages
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Last edited by a moderator:
Chinewalker

Chinewalker

Fleet Admiral
Joined
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Messages
8,902
Re: New Project Handling Issues?

A couple of things...

You mentioned a lot of sanding, filling, painting, etc. - nowhere did I see anything of rebuilding? Is the boat structurally good? No rot or saturated foam flotation?

I see you are running cable & drum steering. You should consider replacing it with a push-pull Teleflex style steering system. Your old cable steering system is prone to the cables stretching, etc. which can be leading to your handling issues at speed. Your motor puts out a lot of torque, enough to stretch the cables one way or the other, which means the motor is steering itself a bit. That steering was fine for the old Merc 40, but the Johnny V4 is a different animal...
 
Stachi

Stachi

Lieutenant Commander
Joined
Jul 14, 2009
Messages
1,671
Re: New Project Handling Issues?

good article...
 
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NZjohnson90

Seaman
Joined
Nov 25, 2009
Messages
64
Re: New Project Handling Issues?

Chinewalker said:
A couple of things...

You mentioned a lot of sanding, filling, painting, etc. - nowhere did I see anything of rebuilding? Is the boat structurally good? No rot or saturated foam flotation?

I see you are running cable & drum steering. You should consider replacing it with a push-pull Teleflex style steering system. Your old cable steering system is prone to the cables stretching, etc. which can be leading to your handling issues at speed. Your motor puts out a lot of torque, enough to stretch the cables one way or the other, which means the motor is steering itself a bit. That steering was fine for the old Merc 40, but the Johnny V4 is a different animal...
Click to expand...

You are right on both points there, I did very little rebuilding, mainly due to budget, skills and lack of a permanent workshop. However, in my limited experience I could not see any major faults with the hull. The floor appeared solid, there are no major cracks or holes and the transom despite being chopped and changed at some point appears solid. Over the few hours that it was out it took on no water whatsoever.

I did not want to remove the floor to check stringers etc as it appears solid and the only way to check under is to cut a section out. The only thing I did was to lay a section of 8mm ply over the existing floor and glass all the seems and edges where you step into the boat (probably overkill but I did not want to crack anything with my 100KG feet.)

The transom had been cut down by the previous owner to fit the short shaft merc so when I replaced it I had to replace the top section of wood and make reinforcing plates out of 5mm marine alu. for each side of the transom. (this had not yet been done on the pics out of the water). Maybe this could have been done better but given my skills I am happy with it, and it appears solid.

Yes it does still run on drum and rope, and I do really want a push pull system but as this will have to wait for funds I temporarily replaced the rope with plastic coated galvanized wire at the advice of guys on here and double checked al the fittings. Hopefully it will be good for a month or two till I find some cash.

The boat does sit surprisingly solid and straight on the plane and the steering feels quite precise, it just doesn't handle chop well at all, corners unnervingly flat and sticks the nose right in the air when coming onto the plane.
 
N

NZjohnson90

Seaman
Joined
Nov 25, 2009
Messages
64
Re: New Project Handling Issues?

Ok I know this an old thread but I thought I should update with the latest news.

I have done a little experimenting, been out a couple more times and think I have solved the problem - or at least reduced it significantly enough.

So as suggested I moved the fuel tank and battery right up front, and added a sand bag that probably weighs around 20kg's maybe?

I found I was still getting water in the splash well though when the boat i stationary, it mostly seems to drain once on the plane but i still feel that is was 10kgs of extra weight sat back there so I just put a bung in it. So far no water has come over the back anyway and I figure if it does i just pull the bung and drain the splash well then replace the bung.

Anyway, handles like a different boat now, that weight in the front seems to make it cut through even relatively heavy chop no worries, before it banged like hell even virtually in ripples.

It still corners very flat but I am getting used to that, I think it is just the hull design. It does feel much more solid and trustworthy in the water though, feels somehow like it grips better now. The only bad thing is a slight prop cavitation when you corner pretty much full lock and full throttle, but I guess you dont ever really have to do that anyway.

Lastly it now pops up and drops onto the plane no worries. I am still experimenting with trim, but it seems that I just have to have the motor trimmed all the way in all the time to get the best performance. Trimming out seems to make little difference at all to the handling and ride until you trim out too far. Guess I can live with that. Hmmm having trouble with my explanations and use of English today for some reason Does that make sense to anyone but me???
 
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