How fast should a boat be for offshore

[Damon7]

Hi everyone I am interested in know if a boat needs to be a curtain speed for offshore fishing. For instance would a old inboard diesel 22ft displacement hull half cabin cruiser that reaches 10 knots max be ok? Or do you need more speed then then to stay on top of waves or get out of bad weather. In my very limited experience when weather gets bad your restricted to slower speeds anyway but is there a minimum for offshore fishing. PS when I say offshore I'm more talking about fishing the outer reefs in FNQ. Thank you for all replys in advance.

[Damon7]

Sorry about the spelling mistakes I meant a certain speed or it may be more correct to say able to reach above a certain speed.

[Jiggy]

Going fast in an offshore boat is kind of relative. You can have a boat that can go 30 knots but, offshore in rough conditions, you may be lucky to run at 10 knots. It's sea conditions and hull design that will determine how fast you can go on the day. A extra deep vee hull can go faster on rough days as long as you're back is OK. Glassy days where you can travel at speed anywhere are not that often, at least around Sydney.

I've thought about the sort of boat I'd have if I lived in FNQ. And a diesel cruiser that hits 10 to 12 knots WOT, but has longish range, hits the sweet spot for me. You're travelling at trolling speed, so you have lures out the whole time. Long range means you can travel to places that are lightly fished, so they'll fish better. Add decent size freshwater tanks and bunks, some sort of kitchen and a fridge and you've got a sweet outfit.

I'm moving up to Hervey Bay in the next couple of years and I am thinking about a boat like this. A 10 hour cruise would see me at the Bunker Group off Seventeen Seventy. And there are lots of other places that I could cruise to as well. It's the sort of boat you should definitely consider.

Cheers

Rob

[Damon7]

Thank you Rob (Jiggy) You've basically described the boat we are purchasing and exactly what you have described is what I liked. I just didn't understand why so many of these slower Diesel boats seem to be spoken of as only inshore cruisers. Thank you very much for your reply very pleased to hear.

Edited December 28, 2022 by Damon7

[Jiggy]

Thanks Damon. I suspect that they are referred to inshore cruisers as they have a flat water hull, designed for the sort of conditions you get in rivers and lakes. Not the sort of boats you really want to run offshore. 

Cheers

Rob

[Damon7]

Here are some photos of the boat. We are putting down a deposit and the owner has kindly agreed to allow us to save up the rest. We have been through a rough time with boats and Brought a few duds and wasted some money and our current Mustang 1500 is a good boat but too small for us and our children. but praise God I think this is a nice boat. We have 5 little children and we just want something safe and comfortable.

Edited December 28, 2022 by Damon7

[Damon7]

Maybe with the photos it'll give a bit more light as to weather it would be capable offshore even though it is a slow diesel cruiser. It's hard too see in the photos but the boat actually has a small keel like a yacht I don't know in my inexperience whether this is good or bad in this style of boat.

Edited December 28, 2022 by Damon7

[Jiggy]

Hmm I'd get it inspected by a marine surveyor. It looks OK but paint can hide lots of issues. There are a lot of dud boats out there and the last thing you want to do, after paying out a pile of money for a boat, is having to spend a lot more fixing issues. A bit of spending on a survey could save you a lot of time, cost and grief. Or confirm that your buying a good boat.

Cheers

Rob

[Damon7]

51 minutes ago, Jiggy said:

Hmm I'd get it inspected by a marine surveyor. It looks OK but paint can hide lots of issues. There are a lot of dud boats out there and the last thing you want to do, after paying out a pile of money for a boat, is having to spend a lot more fixing issues. A bit of spending on a survey could save you a lot of time, cost and grief. Or confirm that your buying a good boat.

Cheers

Rob

Thank you Rob 

I have become aware of what can happen buying boats due to buying one pride that ended up having a wet transom and then our next boat had a new transom that had not yet had a motor mounted but had not been sealed properly and ended up redoing it. I appreciate the advice and understand what you mean. Is it just wet transom stringers I should be aware of or other issues too. And what do you think of the sea capabilities of the boat at a first look.

[Jiggy]

It looks OK, what make and model is it?

 

[Damon7]

8 minutes ago, Jiggy said:

It looks OK, what make and model is it?

 

It's a savage bluefin but it's not like most the bluefins I believe it's a semi-displacement hull but I'm not 100% sure.

[Rebel]

When in doubt read the boating regulations.

Cheers.

[Damon7]

32 minutes ago, Rebel said:

When in doubt read the boating regulations.

Cheers.

Hi Rebel what boating regulations are they? 

[zmk1962]

4 hours ago, Jiggy said:

Going fast in an offshore boat is kind of relative. You can have a boat that can go 30 knots but, offshore in rough conditions, you may be lucky to run at 10 knots. It's sea conditions and hull design that will determine how fast you can go on the day. A extra deep vee hull can go faster on rough days as long as you're back is OK. Glassy days where you can travel at speed anywhere are not that often, at least around Sydney.

I've thought about the sort of boat I'd have if I lived in FNQ. And a diesel cruiser that hits 10 to 12 knots WOT, but has longish range, hits the sweet spot for me. You're travelling at trolling speed, so you have lures out the whole time. Long range means you can travel to places that are lightly fished, so they'll fish better. Add decent size freshwater tanks and bunks, some sort of kitchen and a fridge and you've got a sweet outfit.

I'm moving up to Hervey Bay in the next couple of years and I am thinking about a boat like this. A 10 hour cruise would see me at the Bunker Group off Seventeen Seventy. And there are lots of other places that I could cruise to as well. It's the sort of boat you should definitely consider.

Cheers

Rob

If I can add to Rob's comments and apologies if my views put a dampener on your ideas but I think you were after input so I will speak from my experience. I have been offshore boating regularly since 1990's initially close offshore in 4.5m Quinnies (40hp),  and then out to the shelf in a 6.35m FG vessels (200hp). Now in a 7.2M FG vessel (300hp).

@Damon7 what you suggest can probably be done. And some may do it and I can truly see the attraction - the fuel efficiency and the low acquisition cost. But from my experience seeing a 22ft vessels like that more than 3km offshore is NOT a regular occurrence where I fish (mostly Broken Bay to Jervis Bay NSW). Which begs the question that if it's such a good proposition why is it not popular. 

From my experience, speed is just one consideration.... but you also need to consider things such as:

a) the location where you are boating, do you need to leave through and estuary or do you need to cross a bars?... Bear in mind 10kts WOT is in ideal conditions. The motor generating the max 10kts may not have the power to get you across a bar.  Also will it have the power to control the vessel in larger seas -  to keep the vessel straight coming down the wave and to climb the next in a following sea, or the punch through in a head on swell. 

So when Rob said ...

5 hours ago, Jiggy said:

You can have a boat that can go 30 knots but, offshore in rough conditions, you may be lucky to run at 10 knots.

I agree 100%.... but you need to bear in mind, that vessel has the capability to punch to 30kts -- if it needs to.... and if the opportunity presents itself. The vessel you are looking at does not have that capability. You will be at the mercy of the sea.

b) how long you plan to be offshore ... in Sydney travelling 40km to the shelf, and launching from one of the ramps close to the heads implies this trip is going to be 3-4hrs if you can maintain your 10kts WOT, then add your fishing time and the return trip ... and you need to be planning to spend a significant amount of time offshore in the dark. And thats just a 40km trip. Fitzroy Reef is about 60km out from 1770. 

The longer you spend on a vessel offshore, the more you appreciate or need to have more room - not just for the people but for all the necessities - fuel, food, water, safety gear, ice (for your  catch etc etc) which means a bigger vessel or fewer on board .... all the stuff Rob was mentioning in the 2nd paragraph of his reply ... once you put all that onboard - how much room will there actually be for you, the wife and 5 kids - plus your fishing gear. 

It all starts to add up to fewer people on board or a bigger boat. Also a 30ft travelling at 10kts WOT is a very different proposition and experience to a 20ft vessel in terms of ride and sea worthiness. My friend has a 42ft yacht, max speed on the diesel 8kts but it is a yacht, self-righting and basically unsinkable.

Anyway, they are just my thoughts. I don't want to be a downer, just realistic. 

These are the types of older boats I have seen people buying for regular offshore fishing :

My friend and fellow raider Gil,  Bertram 25s  2x Merccruiser 3L  WOT over 20kts (40kmh)... much bigger than the Savage you are looking at.

My previous boat (barrycuda) 6.35m HainesHunter 635 bought by a semi pro-fisherman who fishes FNQ and plans on 1-3 pax on board ... that boat was no slouch 4sec holeshot and 76kmh top end.  

Cheers Zoran

[Damon7]

Hi Zoran thank you for your input and I definitely understand and appreciate what you are saying and is why I am asking.

Damon.

[zmk1962]

Check out these for some more insights ... I am very conservative when it comes to family/friends and being wide offshore:

... and this ... storm front came up in 10min ... not on any weather forecast. the guys were in a 6m (22ft) boat 32nm off from Sydney.  Would you rather have 200HP+ on the back or something that gives you max 10kts..

Cheers Zoran

[Damon7]

36 minutes ago, zmk1962 said:

Check out these for some more insights ... I am very conservative when it comes to family/friends and being wide offshore:

... and this ... storm front came up in 10min ... not on any weather forecast. the guys were in a 6m (22ft) boat 32nm off from Sydney.  Would you rather have 200HP+ on the back or something that gives you max 10kts..

Cheers Zoran

Thank you Zoran I understand in poor condition or unexpected bad weather to have extra power is something that can help. Do you think the boat I am asking about would do better with a larger motor that could push it better maybe a 75 or 100hp. I am purchasing the boat but putting a bigger motor in is definitely possible in the future. I could maybe even look at putting a turbo on the current motor but not sure if this would make a satisfactory difference or if kits are available.

[slowjigger]

I would be looking at 20 knots top speed as a minimum. With the distances you will be doing anything significantly less would be very tiresome. A bit of speed doesn't hurt either in outrunning bad weather and generally handling and sea keeping.  

Another thing the speed of a displacement boat is governed by a formula. There is a point where adding more horsepower won't see any increase in speed. So, if the boat you are looking at is a displacement hull as you say it you won't get anywhere near 20 knots. That said it looks like a planning hull from your pictures (displacement boats typically have round bottoms):

"As a very general rule the maximum speed of any displacement hull--commonly called its hull speed--is governed by a simple formula: hull speed in knots equals 1.34 times the square root of the waterline length in feet (HS = 1.34 x √LWL). Thus, for example, if you have a 35-foot boat with a waterline length of 28 feet, its hull speed works out to a little over 7 knots (1.34 x √28 = 7.09)".

 

 

Edited December 28, 2022 by slowjigger

[zmk1962]

11 hours ago, Damon7 said:

Thank you Zoran I understand in poor condition or unexpected bad weather to have extra power is something that can help. Do you think the boat I am asking about would do better with a larger motor that could push it better maybe a 75 or 100hp. I am purchasing the boat but putting a bigger motor in is definitely possible in the future. I could maybe even look at putting a turbo on the current motor but not sure if this would make a satisfactory difference or if kits are available.

@slowjigger has given excellent input. So the first step would be to research what is the max hp rating for the savage bluefin. Based on a quick YouTube search seems others have done just that ... then bear in mind, bigger motor = more fuel consumption, lower range etc. 

Wishing you all the best with the project... and lots of fish and fun on the rig.

Cheers Zoran

[Rebel]

@Damon7The NSW Government Boating handbook.

From Transport NSW.

 

[Damon7]

3 hours ago, slowjigger said:

I would be looking at 20 knots top speed as a minimum. With the distances you will be doing anything significantly less would be very tiresome. A bit of speed doesn't hurt either in outrunning bad weather and generally handling and sea keeping.  

Another thing the speed of a displacement boat is governed by a formula. There is a point where adding more horsepower won't see any increase in speed. So, if the boat you are looking at is a displacement hull as you say it you won't get anywhere near 20 knots. That said it looks like a planning hull from your pictures (displacement boats typically have round bottoms):

"As a very general rule the maximum speed of any displacement hull--commonly called its hull speed--is governed by a simple formula: hull speed in knots equals 1.34 times the square root of the waterline length in feet (HS = 1.34 x √LWL). Thus, for example, if you have a 35-foot boat with a waterline length of 28 feet, its hull speed works out to a little over 7 knots (1.34 x √28 = 7.09)".

 

 

Thank you slowjigger

I have researched the capability of displacement hulls and grasp what you are saying. I don't think it is a displacement hull either as you said they are round and deep drafted. I believe it is a semi-displacment hull which from what I understand can plane enough to get above there own bow wave and achieve some faster speeds then hull speed but not completely like a true planning hull. I could be wrong though too. Thank you for your input. I would like to stay with diesel if possible and I'm not sure how hard it will be to find a motor that links up to the same gear box as I know next to nothing about inboards this being my first one.

[Damon7]

59 minutes ago, zmk1962 said:

@slowjigger has given excellent input. So the first step would be to research what is the max hp rating for the savage bluefin. Based on a quick YouTube search seems others have done just that ... then bear in mind, bigger motor = more fuel consumption, lower range etc. 

Wishing you all the best with the project... and lots of fish and fun on the rig.

Cheers Zoran

Thank you Zoran 

I appreciate all the advice and input. I'm sure we'll enjoy the boat. At the moment we go out in a Mustang 1500 that we fully rebuilt so it gets a bit cramped. So I believe it'll be a nice change.

Thank you

Damon.

[rickmarlin62]

The bluefin is a classic old hull  repower it and you will have a very capable boat  i gamefished out of one for years and have a lot of faith in thst hull

[Damon7]

5 minutes ago, rickmarlin62 said:

The bluefin is a classic old hull  repower it and you will have a very capable boat  i gamefished out of one for years and have a lot of faith in thst hull

Hi Rick 

Thank you for your reply. Off the top of your head did yours have the high raised Chines sweep up at the bow or were they flatter joining down lower on the bow. As most the bluefins I see have that flatter chine line and these seem to be the ones with outboard or stern drive. They also have no keel like this one does if you look closely in the photo is has a little keel and the prop sits behind that. This is what lead me to believe it is a semi-displacment. I'm very interested in what you have to say seeing you have owned one before.

Thank you

Damon.

[zmk1962]

16 minutes ago, Damon7 said:

They also have no keel like this one does if you look closely in the photo is has a little keel and the prop sits behind that.

Thats the design of any boat that has a through hull shaft drive prop.  They have a keel and rudder.

The alternatives are, an inboard with the drive leg outside the stern, or a pod with outboards.

Cheers Z