Inflatable boat size.

[munster1967]

I currently have a 2.5 meter air floor inflatable , ( no keel. ) with a 3.3 Hp, that I use on a smaller lake/river. Roughly 200-250 meters wide and 6.8 km long. I want to venture to a much bigger lake to explore islands and do a bit of fishing. This lake/river is probably 2.5 km wide and 100s of km in length and apparently can get very choppy . What size inflatable sib and motor would I need to venture into this bigger body of water safely .I know it's subjective and everybody has a different opinion but I'd like some suggestions. ?? Or is it solely dependent on wind conditions. I don't have the option of a fiberglass fishing boat as I have no where to keep a boat on a trailer.

 

[Slowtack]

I keep my boat on a mooring where it gets a bit rough at times also visit similar exposed moorings... I have a 3.1m inflatable keel type with 2.5 Yamaha 4 stroke... Smaller dinghys tend to have lesser diameter tubes and thus less freeboard in a chop...i am only in the dinghy for 15 minutes... For your purpose... Longer trips in open water i would go for Something bigger than mine... Think of the fetch and likely wave height...

 

[munster1967]

I keep my boat on a mooring where it gets a bit rough at times also visit similar exposed moorings... I have a 3.1m inflatable keel type with 2.5 Yamaha 4 stroke... Smaller dinghys tend to have lesser diameter tubes and thus less freeboard in a chop...i am only in the dinghy for 15 minutes... For your purpose... Longer trips in open water i would go for Something bigger than mine... Think of the fetch and likely wave height...

Thanks for your reply. Would my 3.3 hp motor be big enough in your opinion

 

[Tranona]

You will only get displacement speeds with a 3.3hp on say a 3m with inflatable keel, but the larger tubes will give you both more space and freeboard so potentially drier and more stable. The size of the waters is less important than the conditions and how far you want to go from shore.

 

[munster1967]

You will only get displacement speeds with a 3.3hp on say a 3m with inflatable keel, but the larger tubes will give you both more space and freeboard so potentially drier and more stable. The size of the waters is less important than the conditions and how far you want to go from shore.

Thanks for your reply. Ok so depends on conditions.

 

[Moodysailor]

It's definitely condition dependant. Where we used to live (Teignmouth), i've seen a couple of dinghys struggle to punch the fast flowing tide in a small rubber dinghy and 2.5/3hp motor when loaded.
In Chi harbour, it can be a long way to a swinging mooring and the big area can mean the chop can get up. There a small O/B will be OK, but a drier (read: larger) boat would be preferable.

I also like to think of other uses, we use our tender as a boat in it's own right and go for longer trips (we expolore in it) and wanted a bigger one so we have space and it's safe when it's two of us and our two dogs. Our boat is in refit so we bought a 3.8mtr air v-floor. When the refit is done we'll assess our needs but will probably still have a 3.5-ish mtr with a decent size o/b so that it fits all our needs.

 

[Fr J Hackett]

For what you propose I would use a hard dinghy not an inflatable with a 6HP or more engine.

 

[ashtead]

Your motor is going to be influenced by how heavy you can manage and distance to carry (can you use a trolley?) I am guessing but based on your post it appears the dinghy is either inflated each time you use it or kept in a rack inflated and drageed to water? Have you considered some form of folding hard hull which you store folded and unfold to inflate? Any air deck sib will be wet -we have a 3.1m quicksilver but it’s heavy and we keep deflated . Also have a small 2 person seago . The quicksilver will take a 6hp outboard but how fast can you travel on this lake? Is it subject to speed restrictions ? If you are just pottering I guess a 2 stroke 3.3 eg a mercury type plus a small sib with big tubes eg zodiac type but is the weight ashore going to be okay? Do you have ability to run outboard off separate fuel tank with a fuel line? Tanks on a 3.3 very small.

 

[Minerva]

The Orkney longliner with cuddy is very popular on Scottish lochs - I imagine that style would be a good fit for you too if you’re limited to displacement speeds.

We have a tender similar to your current set up (2.7m air keel with 2.5hp). Once the wind gets to high teens I would use it to go the 500m to shore from my mooring, but not the 1.5nm to the local pub…

 

[Stemar]

Left field option - a sailing dinghy like a wayfarer on a trailer. It would cope with all but the most extreme conditions you're likely to meet there, would be entirely happy with your current OB, and you could use it for dinghy camping trips for days at a time. Extra bonus, the OB is only the reserve power source, and even if that lets you down, you've got oars to get you to the shore.

The disadvantage is that getting to the other end would take days, rather than hours in a planing dinghy, but I reckon it would be a lot more fun.

 

[Tranona]

For what you propose I would use a hard dinghy not an inflatable with a 6HP or more engine.

But he specifically says he cannot do that!

 

[Fr J Hackett]

But he specifically says he cannot do that!

Regardless fishing from an inflatable is not a good solution.

 

[Cerebus]

I am not sure it is to do with boat ‘size’.

I used to have to travel about a mile in a small fibreglass tender with 2.5hp outboard.

3 foot waves would have me sitting on the floorboards to lower the centre of gravity.

Exciting and built in buoyancy meant I was safe if capsize occurred and by careful helming I didn’t get too wet.

I bought an Avon because I was lead to believe they were the most stable of all tenders and that may be so, but not the driest in such conditions and certainly not the best with an outboard in such conditions.

Inflatables can be great and comfy and luxurious even on a calm sunny day.

So I use whichever tender suits the conditions of the day. An inflatable can be stored on the boat whereas a hard tender is always towed in my my case at least.

 

[munster1967]

It's definitely condition dependant. Where we used to live (Teignmouth), i've seen a couple of dinghys struggle to punch the fast flowing tide in a small rubber dinghy and 2.5/3hp motor when loaded.
In Chi harbour, it can be a long way to a swinging mooring and the big area can mean the chop can get up. There a small O/B will be OK, but a drier (read: larger) boat would be preferable.

I also like to think of other uses, we use our tender as a boat in it's own right and go for longer trips (we expolore in it) and wanted a bigger one so we have space and it's safe when it's two of us and our two dogs. Our boat is in refit so we bought a 3.8mtr air v-floor. When the refit is done we'll assess our needs but will probably still have a 3.5-ish mtr with a decent size o/b so that it fits all our needs.

Thanks for your reply and information.

 

[munster1967]

I am not sure it is to do with boat ‘size’.

I used to have to travel about a mile in a small fibreglass tender with 2.5hp outboard.

3 foot waves would have me sitting on the floorboards to lower the centre of gravity.

Exciting and built in buoyancy meant I was safe if capsize occurred and by careful helming I didn’t get too wet.

I bought an Avon because I was lead to believe they were the most stable of all tenders and that may be so, but not the driest in such conditions and certainly not the best with an outboard in such conditions.

Inflatables can be great and comfy and luxurious even on a calm sunny day.

So I use whichever tender suits the conditions of the day. An inflatable can be stored on the boat whereas a hard tender is always towed in my my case at least.

Thanks for your reply. I don’t have the option of a hard shell boat. And trailer.

 

[munster1967]

But he specifically says he cannot do that!

Ok. I don’t have that option. No where to keep hard shell and trailer.

 

[munster1967]

Left field option - a sailing dinghy like a wayfarer on a trailer. It would cope with all but the most extreme conditions you're likely to meet there, would be entirely happy with your current OB, and you could use it for dinghy camping trips for days at a time. Extra bonus, the OB is only the reserve power source, and even if that lets you down, you've got oars to get you to the shore.

The disadvantage is that getting to the other end would take days, rather than hours in a planing dinghy, but I reckon it would be a lot more fun.

Don’t have the option of a trailer. No place for it.

 

[munster1967]

Your motor is going to be influenced by how heavy you can manage and distance to carry (can you use a trolley?) I am guessing but based on your post it appears the dinghy is either inflated each time you use it or kept in a rack inflated and drageed to water? Have you considered some form of folding hard hull which you store folded and unfold to inflate? Any air deck sib will be wet -we have a 3.1m quicksilver but it’s heavy and we keep deflated . Also have a small 2 person seago . The quicksilver will take a 6hp outboard but how fast can you travel on this lake? Is it subject to speed restrictions ? If you are just pottering I guess a 2 stroke 3.3 eg a mercury type plus a small sib with big tubes eg zodiac type but is the weight ashore going to be okay? Do you have ability to run outboard off separate fuel tank with a fuel line? Tanks on a 3.3 very small.

Thanks for your very informative reply.
Yes the sib is inflated /deflated every use. Engine obviously put on and taken off every use. I’m trying to keep the weight of the sib down, my current sib is 28 kg which is no problem. The tube size is 38 cm on my current sib. I could probably man handle 32-33 kg sib without a trolley. . I could use a trolley and I am thinking about this option as I could increase weight of sib and motor. There are no restrictions to speed except at bridges .

 

[vyv_cox]

When we kept a boat on a mooring in Menai Strait we motored about half a mile to reach it. Being strongly tidal and often windy (against each other of course) it was sometimes testing. We had a Zodiac 310 or 320, don't remember, with a 3 HP twin cylinder outboard. Big tubes helped. Although we sometimes got wet, 2 adults and 2 children, we never felt threatened.

 

[Fr J Hackett]

Thanks for your very informative reply.
Yes the sib is inflated /deflated every use. Engine obviously put on and taken off every use. I’m trying to keep the weight of the sib down, my current sib is 28 kg which is no problem. The tube size is 38 cm on my current sib. I could probably man handle 32-33 kg sib without a trolley. . I could use a trolley and I am thinking about this option as I could increase weight of sib and motor. There are no restrictions to speed except at bridges .

If you can't use a trolly there are wheels that you can attach to the transom of an inflatable they lift up out of the water when motoring. Also given that you have to lift everything and transport it then the weight of the engine is going to be your limiting factor in that department which in turn will limit the size of the inflatable.
You don't say which waterways you are going to be using them on but be aware their are usually speed limits on rivers and even lakes so again the size of engine might not be that critical.