Hook In Hull - How Much Is Too Much?

[Hydro Mark]

I have a 1964 17' fiberglass v-bottom runabout with a slight hook caused sitting on a trailer roller for years. My question is, is this something I should do something about? I don't have the measurement (not enough hands) yet, but here is a photo. It looks like it starts where my finger tips are, but is very pronounced where the roller was. The boat is off the rollers now.


Thanks,
Mark

 

[SWD]

Re: Hook In Hull - How Much Is Too Much?

I honestly dont think you can do a bunch about it now but others may prove me wrong. I doubt seriously if that would impair overall performance. IMHO just forget about it.

 

[colbyt]

Re: Hook In Hull - How Much Is Too Much?

Like SWD, I am as far from an expert as you will meet here. I just don't see it being a problem. I imagine almost every boat more than a few years old has some minor distortion somewhere.

 

[Silverbullet555]

Re: Hook In Hull - How Much Is Too Much?

I wouldn't be worried about that on a 50 year old boat.

 

[BonairII]

Re: Hook In Hull - How Much Is Too Much?

Probably not going to affect performance much, if at all. I would guess that the higher the speed is....the more effect a "hook" would have.


I'd be more concerned about the boat being waterlogged etc, at that age....then a slight hook.

 

[jigngrub]

Re: Hook In Hull - How Much Is Too Much?

To get a better idea of just how much hook you have you need to pull a string from the bow to the transom along the keel. It'll be more than it looks like with that level.

Has your boat ever been restored? Have you ever wanted to restore a boat? Now would be a good time to find out. A 50 yr. old boat that's never been restored could probably use a good going through... transom, stringers, and deck. Not to mention the addition of updated floatation foam.

 

[blackhawk180]

Re: Hook In Hull - How Much Is Too Much?

I'm thinking the cure might be worse than the disease. If you don't have any waterlogging as bonairll mentioned, I'd launch it and see what happens.

 

[Ned L]

Re: Hook In Hull - How Much Is Too Much?

What hp engine does it have? A lot of the answer to your question depends on the top speed of the boat. Up to about 25 knots a slight hook won't cause much of a problem (if any). As the speed increases above that the problem becomes more pronounced.

 

[jigngrub]

Re: Hook In Hull - How Much Is Too Much?

I'm thinking the cure might be worse than the disease.

If you don't like to work with your hands it will be worse, but if you like the idea of getting a like new boat for a small fraction of the cost of a new one... it's a pretty good deal.

I suspect the OPs boat sat on the trailer for years exposed to the elements, the foam (if there is any) became waterlogged and heavy and the stringers became rotten and weak. When all of the interior structural support was gone the boat sagged.

I personally would start checking for rot in the transom, deck, and stringers. Seaworthy boats don't sag or hook hulls.

 

[lakegeorge]

Re: Hook In Hull - How Much Is Too Much?

Don't worry about it, I don't see it hurting anything.

 

[JimS123]

Re: Hook In Hull - How Much Is Too Much?

The roller didn't cause the hook - the guy that set up the trailer did because he misaligned them.
OR......the core of your boat is rotten and that caused the deformation.

Why are you asking in the first place? Do you notice performance issues? Or, are you just wondering and you haven't had the boat in the water yet?

Many moons ago I had a hook that was just like that (at least what I can see from the picture). The boat ran fine with a 40 HP motor, but when I upgraded to a 60 HP it porpoised uncontrollably. I ended up getting rid of the boat. The other thing was that mine was quite near the transom.

As others have said, speed capabilty has a lot to do with it. If you haven't run it yet, do so and check back again.

 

[Hydro Mark]

Re: Hook In Hull - How Much Is Too Much?

Thanks for all the great replies guys. I should've given more info.

I just had the boat out for the first time to shake it down. I'm now putting a new interior in. Here are the results:

Motor ran great. 43 mph with 4 people at 6,000. Max is somewhere around 5,400 so I hope to get close to 50 mph with a new prop.

The boat ran extremely flat. This was also noted by professional water skiers on the beach. Trimmed up and still flat. Didn't have time to trim up more. It's manual trim. This is the reason for my question. I only have two more holes left to trim up.

The deck and transom are super solid. This brand, Hydro Swift, supposedly had good construction techniques. It also has mahogany stringers and transom. Since all is good on the outside, the only thing I could do is core some random holes in the keel and stringers to check for rot. Don't really want to do that though.

Thanks again for the help.
Mark

 

[BonairII]

Re: Hook In Hull - How Much Is Too Much?

What motor are you running? Might be a stretch hoping for 7mph increase with a diff prop.

A 2" increase in pitch should lower your rpm approx 400rpms and put you where you need to be.

Find out exactly what rpm range the motor manufacturer recommends and prop your motor to spin near the top of that range. An accurate tachometer is needed to prop correctly....Do NOT guess the rpms based on your ear.

 

[Hydro Mark]

Re: Hook In Hull - How Much Is Too Much?

What motor are you running? Might be a stretch hoping for 7mph increase with a diff prop.

A 2" increase in pitch should lower your rpm approx 400rpms and put you where you need to be.

Find out exactly what rpm range the motor manufacturer recommends and prop your motor to spin near the top of that range. An accurate tachometer is needed to prop correctly....Do NOT guess the rpms based on your ear.

Thanks BonairII. The motor is a '68 Merc 1250 125 hp. The tach is a Mercury tach specifically for this Thunderbolt-ignitioned motor. The tach matches my Snap-on timing light at idle so I'm assuming its good. Most sources say the max should be approx 5,400 rpms. The current prop is a 13.25" x 17 pitch aluminum Merc prop. According to the chart I have for this motor, a 17 pitch should get me 28-35 mph, 19= 33-40 mph, 21= 38-45 mph. 4800-5300 as rpm range. Was thinking about going to a 21". Too big of a jump?

 

[Hydro Mark]

Re: Hook In Hull - How Much Is Too Much?

Here's the boat

 

[BonairII]

Re: Hook In Hull - How Much Is Too Much?

Might be too big of a jump.....maybe not though. You need to get your rpm down about 700-800rpm, so a 4" increase might be good.

I would experiment with both...if you can borrow those 2 diff size props. IIWM, I'd prop as close to the 5300rpms as possible. do your testing with a realistic load on your boat. If you avg having 2-4 people onboard....then test props with 3 people in the boat, so you can find a good middle ground prop.

I have 2 props I use for my boat. A 17" for general purpose....and a 15" for more torque(pulling a tube, 4 passengers etc)

You'll probably find that having a 19" AND a 21" will be perfect for your motor

 

[Hydro Mark]

Re: Hook In Hull - How Much Is Too Much?

Might be too big of a jump.....maybe not though. You need to get your rpm down about 700-800rpm, so a 4" increase might be good.

I would experiment with both...if you can borrow those 2 diff size props. IIWM, I'd prop as close to the 5300rpms as possible. do your testing with a realistic load on your boat. If you avg having 2-4 people onboard....then test props with 3 people in the boat, so you can find a good middle ground prop.

I have 2 props I use for my boat. A 17" for general purpose....and a 15" for more torque(pulling a tube, 4 passengers etc)

You'll probably find that having a 19" AND a 21" will be perfect for your motor

Ok. Sounds like good advice. Thanks.

 

[Chris1956]

Re: Hook In Hull - How Much Is Too Much?

A 19" pitch prop will lower max RPM to 5600, which is good for that motor. Is the bow plowing water? If not, the hull is likely not hooked enought to matter.

A lot of boats of that age had straight vee hulls and ran dead flat on the water. It was the design.

 

[Hydro Mark]

Re: Hook In Hull - How Much Is Too Much?

A 19" pitch prop will lower max RPM to 5600, which is good for that motor. Is the bow plowing water? If not, the hull is likely not hooked enought to matter.

A lot of boats of that age had straight vee hulls and ran dead flat on the water. It was the design.

I don't think it's plowing and yes, it's a straight vee. If that's the design, I guess there's nothing I can do and you're right, it runs almost dead flat but bow is out just barely. I was in perfectly flat water. I think out in the harbor, it may be an issue. Thanks for the reply.

 

[coolbri70]

Re: Hook In Hull - How Much Is Too Much?

my boat has a similar hull, it also rides low up front, seems to part rough water well, try trimming out to get it up, on mine it hits wakes harder up, with bow down its a smoother ride, just don't go submarining into a wave, it will get your hair wet:laugh: